Metal Complexes with Dibenzo[f,h]quinoxalines

ABSTRACT

This invention relates to electroluminescent metal complexes of the formula electronic devices comprising the metal complexes and their use in electronic devices, especially organic light emitting diodes (OLEDs). The metal complexes of formula (I) show high emission efficiency, excellent vaporizability, thermal stability, processing stability, high charge carrier mobilities, low turn-on voltage and high temperature stability of the emission color.

This invention relates to electroluminescent metal complexes withdibenzo[f,h]quinoxalines, a process for their preparation, electronicdevices comprising the metal complexes and their use in electronicdevices, especially organic light emitting diodes (OLEDs). The metalcomplexes with dibenzo[f,h]quinoxalines show high emission efficiency,excellent vaporiza-bility, thermal stability, processing stability, highcharge carrier mobilities, low turn-on volt-age and high temperaturestability of the emission color.

JP2005298483 describes an iridium complex, such as, for example,

which can be used for the luminous element and is also suitable for anorganic electroluminescent element material, an electrochemiluminescent(ECL) element material, a luminescence sensor, a photosensitizer, adisplay, etc., its preparation method and a luminous material.

KR20060079625 relates to phosphorescent red-emitting iridium complexes,such as, for example,

and organic electroluminescent device comprising same. Z. Liu et al,Adv. Funct. Mat. 2006, 16, 1441, describe the use of the complexes

wherein R¹ is t-butyl and R² is

or R¹ is t-butyl and R² is

for highly efficient non-doped organic light emitting diodes.

J.-P. Duan et al., Adv. Mat. 2003, 15, 224, describe the use of thecomplexes

as orange-red emitters in an OLED.

KR20060036670 relates to phosphorescent iridium complexes and organicelectroluminescent devices comprising the same. The followingphosphorescent iridium complexes are explicitly disclosed

KR20060079625 relates to iridium complexes represented by the formula

wherein R₁, R₂, R₃, R₆, R₇ and R8 are independently H, a halogen atom, acarboxy group, an amino group, a cyano group, a nitro group, aC₁-C₆alkyl group, a C₆-Ci₈aryl group, a C₁-C₆alkoxy group or aC₄-C₆hetero ring containing a hetero atom such as S or N, or R₂ and R₃can be fused to form an aromatic ring; R₄ and R₅ are independently H, aC₁-C₆ alkyl group, a C₁-C₆haloalkyl group, a C₆-C₁₈aryl group, aC₄-C₁₂hetero ring, an amino group substituted with an alkyl or arylgroup, a C₁-C₆alkoxy group, a cyano group or a nitro group; and X is CHor N (claim 1), and an OLED device containing the metal complex offormula (1).

EP1939208A1 is directed to an organometallic complex having a structurerepresented by the general formula

wherein Ar represents an aryl group having 6 to 25 carbon atoms;A¹ represents any one of hydrogen, an alkyl group having 1 to 4 carbonatoms, and an alkoxy group having 1 to 4 carbon atoms;A² to A⁸ each represent any one of hydrogen, an alkyl group having 1 to4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and ahalogen group;M₁₀ represents a metal of Group 9 elements and Group 10 elements;L₁₀ represents a monoanionic ligand; andu is 2 when the metal is a Group 9 element, and u is 1 when the metal isa Group 10 element.

WO2009069535 relates to a light-emitting element comprising alight-emitting layer between a first electrode and a second electrode,wherein the light-emitting layer comprises a first organic compoundhaving a hole-transporting property, a second organic compound having anelectron-transporting property, and an organometallic complex, wherein aligand of the organometallic complex has a dibenzo[th]quinoxalineskeleton, especially a 2-aryldibenzo[f,h]quinoxaline derivative, andwherein a central metal of the organometallic complex is a Group 9 orGroup 10 element.

WO2009157498 relates to metal complexes of the formula

wherein R¹ to R¹³ represent any of hydrogen, an alkyl group having 1 to4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms;M represents a central metal selected from a Group 9 or Group 10elements;L₁₀ represents a monoanionic ligand; and u is 2 when the central metalis a Group 9 element or 1 when the central metal is a Group 10 element;and their use in light emitting devices.

WO2009100991 relates to metal complexes of the formula

and their use in OLEDs. Among others compounds of formula

wherein R¹ is C₂-C₁₀alkyl, R² is H, or CH₃, and L is

are preferred.

WO2005049762 relates to a light-emitting device comprising at least asubstrate, an anode, a light-emitting layer and a cathode whereby thelight-emitting layer contains an iridium complex IrL₃ and whereby atleast two ligands L are a dibenzoquinoline. WO2005049762 relates inparticular to the complexesIr(dibenzo[f,h]quinoline)₂(pentane-2,4-dionate) andIr(dibenzo[f,h]quinoline)₃ which emit light with a wavelength ofλ_(max)=545 nm and λ_(max)=595 nm respectively:

However, there is a continuing need for electroluminescent compounds,especially orange, or red emitters, having improved performance, such asfor example, compounds having high emission efficiency, excellentvaporizability, thermal stability, processing stability, high chargecarrier mobilities, low turn-on voltage and high temperature stabilityof the emission color.

Surprisingly, it was found that compounds of formula I, wherein R³ andR⁸ are C₁-C₈alkyl, show a narrower full width half maximum (FWHM) of theemission, such as, for example, by a narrowing of the green portion ofthe emission, in comparison to compounds of formula I known from theprior art, wherein R³ and R⁸ are H. Compounds of formula I, wherein R¹is branched Cl-Csalkyl, show an even narrower FWHM of the emission. Dueto the narrower FWHM of the emission the compounds of formula I show amore saturated orange to red emission, with deeper orange to red colorindex coordinates (CIE x,y), when used as emitter in an organic lightemitting device (OLED), surprisingly by the introduction of alkyl groupsat the appropriate positions alone. Moreover, alkyl substituents areparticularly important because they offer a wide range of tunability interms of evaporation temperature, solubility, energy levels, deviceefficiency etc. Moreover they are stable as functional groups chemicallyand in device operation when applied appropriately.

Accordingly the present invention is directed to compounds (metalcomplexes) of the formula

whereinR¹ is H, C₃-C₈cycloalkyl, which is optionally substituted by C₁-C₈alkylor C₁-C₈perfluoroalkyl; or C₁-C₈alkyl, orR¹ is a group of formula

R² is H, or C₁-C₈alkyl, orR¹ and R² together form a ring —(CH₂)₃—, or —(CH₂)₄—, which areoptionally substituted by one, or two C₁-C₈alkyl and/or by one, or twoC₁-C₈perfluoroalkyl;R³ and R⁸ are independently of each other C₁-C₈alkyl,—Si(C₁-C₈alkyl)_(3,) or C₃-C₈cycloalkyl;n1 is 0, or an integer of 1 to 5, n2 is 0, or an integer of 1 to 3, n3is 0, or an integer of 1 to 4,Y is —O—, —S—, —NR³⁰—, or —CR³¹R³²—;R⁴ is C₁-C₈alkyl, cyclohexyl, F, C₁-C₈perfluoroalkyl, or NR⁷R⁹,R^(4′) is H, C₁-C₈alkyl, cyclohexyl, or C₁-C₈perfluoroalkyl, especiallyH, C₁-C₈alkyl, or CF₃, very especially H, or C₁-C₈alkyl,R⁵ and R⁶ are independently of each other C₁-C₈alkyl, or cyclohexyl;<CWU-Call number =“ 41 ” />R⁷ and R⁹ are independently of each other a group of formula

R¹¹¹, R^(11′) and R^(11″) are independently of each other C₁-C₈alkyl, orC₁-C₈alkoxy; orR⁷ and R⁹ together with the nitrogen atom to which they are bonded forma group of formula

m′ is 0, 1, or 2;R¹⁰ can be the same or different at each occurence and is C₁-C₈alkyl, orC₃-C₈cycloalkyl,R³⁰ is C₁-C₁₈alkyl; a group of formula

p1 is 0, or an integer of 1 to 3, p2 is 0, or an integer of 1 to 2, p3is 0, or an integer of 1 to 2,R³¹ and R³² are independently of each other hydrogen, C₁-C₁₈alkyl,C₇-C₂₅arylalkyl, or a phenyl group, which optionally can be substitutedone to three times with C₁-C₈alkyl and/or C₁-C₈alkoxy,m″ can be the same or different at each occurence and is 0, 1, 2, or 3;

M is Pt, Pd, Rh, Ir, or Re,

L is a mono-, or bi-dentate ligand,if L is a monodentate ligand,

m is 0, or 2, and n is 1, or 2, if M is Pd, or Pt, m is 0, 2, or 4, andn is 1, 2, or 3, if M is Rh, Ir or Re,

if L is a bidentate ligand,

m is 0, or 1, and n is 1, or 2, if M is Pd, or Pt, m is 0, 1, or 2, andn is 1,2, or 3, if M is Rh, Ir or Re.

The compounds of the present invention are preferably orange, or redemitters having a λ_(max) above about 580 nm, especially above about 610nm and very especially above about 615 nm. The dibenzo[f,h] quinoxalinecompound or compounds should have a colour coordinate (CIE x,y) ofbetween about (0.62, 0.38) and about (0.68, 0.32), especially a colourcoordinate of between about (0.63, 0.37) and about (0.68, 0.32), veryespecially a colour coordinate of between about (0.64, 0.36) and about(0.68, 0.32).

The metal complexes with dibenzo[f,h]quinoxalines show high emissionefficiency, excellent vaporizability, thermal stability, processingstability, high charge carrier mobilities, low turn-on voltage and hightemperature stability of the emission color.

FIG. 1 provides a plot of the EL intensity of compounds CC-1 and A-17 asa function of wavelength.

FIG. 2 provides a plot of the EL intensity of compounds CC-3 and A-79 asa function of wavelength.

According to the present invention the metal complex comprise at least adibenzo[f,h]-quinoxaline ligand, i.e. it may comprise two or threedibenzo[f,h] quinoxaline ligands. The term “ligand” is intended to meana molecule, ion, or atom that is attached to the coordination sphere ofa metallic ion. The term “complex”, when used as a noun, is intended tomean a compound having at least one metallic ion and at least oneligand. The term “group” is intended to mean a part of a compound, sucha substituent in an organic compound or a ligand in a complex. The term“facial” is intended to mean one isomer of a complex, Ma₃b₃, havingoctahedral geometry, in which the three “a” groups are all adjacent,i.e. at the corners of one triangular face of the octahedron. The term“meridional” is intended to mean one isomer of a complex, Ma₃b₃, havingoctahedral geometry, in which the three “a” groups occupy threepositions such that two are trans to each other, i.e. the three “a”groups sit in three coplanar positions, forming an arc across thecoordination sphere that can be thought of as a meridion. The phrase“adjacent to” when used to refer to layers in a device, does notnecessarily mean that one layer is immediately next to another layer.

The metal complexes of the present invention are characterized in thatat least one ligand is derived from a dibenzo[f,h]quinoxaline compound.Suitable dibenzo[f,h]quinoxalines, or intermediates thereof, are knownor can be produced according to known procedures. The synthesis ofsuitable dibenzo[f, h]quinoxaline and intermediates thereof is, forexample, described in J.-P. Duan et al., Adv. Mat. 2003, 15, 224,WO2006/097419 and WO2008031743A1, as well as the references citedtherein.

The compounds have preferably a structure (Va), (Vb), (Vc), (VIa),(VIb), or (VIc) below:

wherein

M² is Rh, Ir or Re, M⁴ is Pd, or Pt,

L is a bidentate ligand, andL″′ is a monodentate ligand, andR¹, R², R³ and R⁸ are as defined above. More preferred are compounds offormula (Va), (Vb), (Vc), (VIa), (VIb), or (VIc), wherein R² is H.

The metal M is selected from Ir, Rh and Re as well as Pt and Pd, whereinPt and Ir are preferred and Ir is most preferred.

In a preferred embodiment R¹ is C₃-C₈cycloalkyl, which is optionallysubstituted by one, or two C₁-C₈alkyl and/or by one, or twoC₁-C₈perfluoroalkyl; or C₁-C₈alkyl, or R¹ and R²together form a ring—(CH₂)₃—, or —(CH₂)₄—, which are optionally substituted by one, or twoC₁-C₈alkyl and/or by one, or two C₁-C₈perfluoroalkyl. R² is preferablyH. More preferred, R¹ is C₃-C₈cycloalkyl, or C₁-C₈alkyl, R²is H; or R¹and R²together form a ring —(CH₂)₄—. Most preferred R¹ isC₃-C₈cycloalkyl, or C₁-C₈alkyl, such as, for example, methyl, ethyl,iso-butyl, tert-butyl, or neopentyl. ^(R2) is preferably H.

In another preferred embodiment R¹ is a group of formula

especially

even more especially

very especially

R⁴ is H, C₁-C₈alkyl, cyclohexyl, F, C₁-C₈perfluoroalkyl, or NR⁷R⁹,especially C₁-C₈alkyl, CF₃, or NR⁷R⁹, even more especially CF₃, NR⁷R⁹,very especially NR⁷R⁹,R⁵ and R⁶ are independently of each other H, C₁-C₈alkyl, especially H,or C₁-C₈alkyl;R⁴″ is C₁-C₈alkyl, cyclohexyl, F, C₁-C₈perfluoroalkyl, NR⁷R⁹, especiallyC₁-C₈alkyl, or CF₃, NR⁷R⁹, even more especially C₁-C₈alkyl, or CF₃, veryespecially C₁-C₈alkyl,R⁷ and R⁹are independently of each other

orR⁷ and R⁹ together with the nitrogen atom to which they are bonded forma group of formula

R¹⁰ is H, or C₁-C₈alkyl, and R² is H.

In another preferred embodiment R¹ is a group of formula

especially

more especially

wherein R^(4′) is H, C₁-C₈alkyl, cyclohexyl, or C₁-C₈perfluoroalkyl,especially H, C₁-C₈alkyl, or CF₃, very especially H, or C₁-C₈alkyl.

If R¹ is a group of formula

groups of formula

are preferred and groups of formula

are even more preferred.

For the above described preferred embodiments for R¹ the followingpreferences for R², R³, R⁸, L and M apply:

M is preferably Pt and Ir, more preferably Ir.

L is preferably a group of formula

more preferably

R² is preferably H.

R³ and R⁸ are preferably C₁-C₈alkyl, Si(C₁-C₄alkyl)₃, orC₃-C₆cycloalkyl.

If R³ and R⁸ represent a cycloalkyl group, they are preferablycyclopropyl, cyclobutyl, or cyclopentyl.

If R³ and R⁸ represent a trialkylsilyl group, they are preferablytrimethyl silyl.

If R³ and R⁸ represent a C₁-C₈alkyl group, they are preferablyC₁-C₅alkyl, especially methyl, ethyl, iso-butyl, or neopentyl.

Monodentate ligands are preferably monoanionic. Such ligands can have Oor S as coordinating atoms, with coordinating groups such as alkoxide,carboxylate, thiocarboxylate, dithiocarboxylate, sulfonate, thiolate,carbamate, dithiocarbamate, thiocarbazone anions, sulfonamide anions,and the like. In some cases, ligands such as β-enolates can act asmonodentate ligands. The monodentate ligand can also be a coordinatinganion such as halide, nitrate, sulfate, hexahaloantimonate, and thelike. Examples of suitable monodentate ligands are shown below:

The monodentate ligands are generally available commercially.

In a preferred embodiment of the present invention the ligand is a(monoanionic) bidentate ligand. In general these ligands have N, O, P,or S as coordinating atoms and form 5- or 6-membered rings whencoordinated to the iridium. Suitable coordinating groups include amino,imino, amido, alkoxide, carboxylate, phosphino, thiolate, and the like.Examples of suitable parent compounds for these ligandsincludep-dicarbonyls (β-enolate ligands), and their N and S analogs;amino carboxylic acids (aminocarboxylate ligands); pyridine carboxylicacids (iminocarboxylate ligands); salicylic acid derivatives (salicylateligands); hydroxyquinolines (hydroxyquinolinate ligands) and their Sanalogs; and diarylphosphinoalkanols (diarylphosphinoalkoxide ligands).

Examples of such bidentate ligands L are

wherein R¹¹ and R¹⁵ are independently of each other hydrogen,C₁-C₈alkyl, CC₆-C₁₈aryl, which can optionally be substituted byC₁-C₈alkyl; cyclopentyl, which can optionally be substituted byC₁-C₈alkyl, or phenyl; cyclohexyl, which can optionally be substitutedby C₁-C₈alkyl, or phenyl; C₂-C₁₀heteroaryl, or C₁-C₈perfluoroalkyl,R¹² and R¹⁶ are independently of each other hydrogen, C₆-C₁₈aryl, orC₁-C₈alkyl, orR12 is a group of formula

R¹³ and R¹⁷ are independently of each other hydrogen, C₁-C₈alkyl,C₆-C₁₈aryl, C₂-C₁₀heteroaryl, C₁-C₈perfluoroalkyl, or C₁-C₈alkoxy, andR¹⁴ is C₁-C₈alkyl, C₆-C₁₀aryl, or C₇-C₁₁aralkyl,R¹⁸ is C₆-C₁₀aryl,R¹⁹ is C₁-C₈alkyl, C₁-C₈perfluoroalkyl,R²⁰ is C₁-C₈alkyl, or C₆-C₁₀aryl,R21 is hydrogen, C₁-C₈alkyl, or C₁-C₈alkoxy, which may be partially orfully fluorinated,R²² and R²³ are independently of each other C_(q)(H+F)_(2q+1), orC₆(H+F)₅, R²⁴ can be the same or different at each occurrence and isselected from H, or C_(q)(H+F)_(2q+1),q is an integer of 1 to 24, p is 2, or 3, andR⁴⁶ is C₁-C₈alkyl, C₆-C₁₈aryl, or C₆-C₁₈aryl, which is substituted byC₁-C₈alkyl.

Examples of suitable phosphino alkoxide ligands

are listed below:

-   3-(diphenylphosphino)-1-oxypropane [dppO]-   1,1-bis(trifluoromethyl)-2-(diphenylphosphino)-ethoxide [tfmdpeO].

Examples of particularly suitable compounds HL,

from which the ligands L are derived, include

The hydroxyquinoline parent compounds, HL, can be substituted withgroups such as alkyl or alkoxy groups which may be partially or fullyfluorinated. In general, these compounds are commercially available.Examples of suitable hydroxyquinolinate ligands, L, include:

-   8-hydroxyquinolinate [8hq]-   2-methyl-8-hydroxyquinolinate [Me-8hq]-   10-hydroxybenzoquinolinate [10-hbq]

In a further embodiment of the present invention the bidentate ligand Lis a ligand of formula

wherein the ring A,

represents an optionally substituted aryl group which can optionallycontain heteroatoms, the ring B,

represents an optionally substituted nitrogen containing aryl group,which can optionally contain further heteroatoms, or the ring A may betaken with the ring B binding to the ring A to form a ring.

The preferred ring A includes a phenyl group, a substituted phenylgroup, a naphthyl group, a substituted naphthyl group, a furyl group, asubstituted furyl group, a benzofuryl group, a substituted benzofurylgroup, a thienyl group, a substituted thienyl group, a benzothienylgroup, a substituted benzothienyl group, and the like. The substitutenton the substituted phenyl group, substituted naphthyl group, substitutedfuryl group, substituted benzofuryl group, substituted thienyl group,and substituted benzothienyl group include C₁-C₂₄alkyl groups,C₂-C₂₄alkenyl groups, C₂-C₂₄alkynyl groups, aryl groups, heteroarylgroups, C₁-C24alkoxy groups, C₁-C24alkylthio groups, a cyano group,C₂-C₂₄acyl groups, C₁-C24alkyloxycarbonyl groups, a nitro group, halogenatoms, alkylenedioxy groups, and the like.

In said embodiment the bidentate ligand

is preferably a group of formula

wherein R²¹¹, R²¹², R²¹³, R²¹⁴ are independently of each other hydrogen,C₁-C₂₄alkyl, C₂-C₂₄alkenyl, C₂-C24alkynyl, aryl, heteroaryl,C₁-C₂₄alkoxy, Ci₁-C₂₄alkylthio, cyano, acyl, alkyloxycarbonyl, a nitrogroup, or a halogen atom; the ring A represents an optionallysubstituted aryl or heteroaryl group; or the ring A may be taken withthe pyridyl group binding to the ring A to form a ring; the alkyl group,alkenyl group, alkynyl group, aryl group, heteroaryl group, alkoxygroup, alkylthio group, acyl group, and alkyloxycarbonyl grouprepresented by R²¹¹, R²¹², R²¹³, and R²¹⁴ may be substituted; or

R²¹³ and R²¹⁴ or R²¹² and R²¹³ are a group of formula

wherein A⁴¹, A⁴², A⁴³, A⁴⁴, A⁴⁵, and A⁴⁶ are as defined above.

Examples of preferred classes of such bidentate ligands L are compoundsof the formula

especially

wherein Y is S, O, NR²⁰⁰, wherein R²⁰⁰ is C₁-C₄alkyl, C₂-C₄alkenyl,optionally substituted C₆-C₁₀-aryl, especially phenyl, —(CH2)_(r)—Ar,wherein Ar is an optionally substituted C₆-C₁₀aryl, especially

a group —(CH₂)_(r′)—X²⁰, wherein r′ is an integer of 1 to 5, X²⁰ ishalogen, especially F, or Cl; hydroxy, cyano, —O—C₁-C₄alkyl,di(C₁-C₄alkyl)amino, amino, or cyano; a group—(CH₂)_(r)OC(O)(CH₂)_(r″)-CH₃, wherein r is 1, or 2, and r″ is 0, or 1;

—NH-Ph, —C(O)CH₃, —CH₂—O—(CH₂)₂—Si(CH₃)₃, or

Another preferred class of ligands L is described in WO06/000544, ofwhich the following can advantageously be used according to the presentinvention:

whereinQ¹ and Q² are independently of each other hydrogen, C₁-C₂₄alkyl, orC₆-C₁₈aryl,A^(21′) is hydrogen,A^(22′) is hydrogen, or C₆-C₁₀aryl,A^(23′) is hydrogen, or C₆-C₁₀aryl,A^(24′) is hydrogen, or

A^(23′) and A^(24′), or A^(23′) and A^(24′) together form a group

wherein R^(205′), R^(206′), R^(207′) and R^(208′) are independently ofeach other H, or C₁-C₈alkyl,R^(42′) is H, F, C₁-C₄alkyl, C₁-C₈alkoxy, or C₁-C₄perfluoroalkyl,R^(43′) is H, F, C₁-C₄alkyl, C₁-C₈alkoxy, C₁-C₄perfluoroalkyl, orC₆-C₁₀aryl,R^(44′) is H, F, C₁-C₄alkoxy, C₁-C₈alkoxy,or C₁-C₄perfluoroalkyl, andR^(45′) is H, F, C₁-C₄alkyl, C₁-C₈alkoxy, or C₁-C₄perfluoroalkyl.

Another preferred class of bidentate ligands L is a compound of formula

wherein R²¹⁴ is hydrogen, halogen, especially F, or Cl; C₁-C₄alkyl,C₁-C₄perfluoroalkyl, C₁-C₄alkoxy, or optionally substituted C₆-C₁₀oaryl,especially phenyl,R²¹⁵ is hydrogen, halogen, especially F, or Cl; C₁-C₄perfluoroalkyl,optionally substituted C₆-C₁₀aryl, especially phenyl, or optionallysubstituted C₆-C₁₀perfluoroaryl, especially C₆F₅,R²¹⁶ is hydrogen, C₁-C₄alkyl, C₁-C₄perfluoroalkyl, optionallysubstituted C₆-C₁₀aryl, especially phenyl, or optionally substitutedC₆-C₁₀perfluoroaryl, especially C₆F₅,R²¹⁷ is hydrogen, halogen, especially F, or Cl; nitro, cyano,C₁-C₄alkyl, C₁-C₄perfluoroalkyl, C₁-C₄alkoxy, or optionally substitutedC₁-C₄aryl, especially phenyl,R²¹⁰ is hydrogen,R²¹¹ is hydrogen, halogen, especially F, or Cl; nitro, cyano,C₁-C₄alkyl, C₁-C₄alkoxy, C₂-C₄alkenyl, C₁-C₄perfluoroalkyl,—O-C₁-C₄perfluoroalkyl, tri(C₁-C₄alkyl)silanyl, especiallytri(methyl)silanyl, optionally substituted C₆-C₁₀aryl, especiallyphenyl, or optionally substituted C₆-C₁₀perfluoroaryl, especially C₆F₅,R²¹² is hydrogen, halogen, especially F, or Cl; nitro, hydroxy,mercapto, amino, C₁-C₄alkyl, C₂-C₄alkenyl, C₁-C₄perfluoroalkyl,C₁-C₄alkoxy, —O-C₁-C₄perfluoroalkyl, —S-C₁-C₄alkyl,tri(C₁-C₄alkyl)siloxanyl, optionally substituted —O-C₆-C₁₀aryl,especially phenoxy, cyclohexyl, optionally substituted C₆-C₁₀aryl,especially phenyl, or optionally substituted C₆-C₁₀perfluoroaryl,especially C₆F₅, andR²¹³ is hydrogen, nitro, cyano, C₁-C₄alkyl, C₂-C₄alkenyl,C₁-C₄perfluoroalkyl, —O -C₁-C₄perfluoroalkyl, tri(C₁-C₄alkyOsilanyl, oroptionally substituted C₆-C₁₀aryl, especially phenyl.

Specific examples of bidentate ligands L are the following compounds(X-1) to (X-57):

In case of the metal complex (L^(a))₂IrL′ three isomers can exist.

In some cases mixtures of isomers are obtained. Often the mixture can beused without isolating the individual isomers. The isomers can beseparated by conventional methods, as described in A. B. Tamayo et al.,J. Am. Chem. Soc. 2003, 125, 7377-7387.

The at present most preferred ligands L are listed below:

especially

In a preferred embodiment the present invention is directed to compoundsof formula

wherein M² is iridium,R¹ is C₁-C₈alkyl,

R² is H; or

R¹ and R² together form a ring —(CH₂)₃—, or —(CH₂)₄—, which areoptionally substituted by one or two C₁-C₈alkyl,R³ and R⁸ are C₁-C₈alkyl, —Si(C₁-C₄alkyl)₃, or C₃-C₆cycloalkyl and

L is

If R¹ and R²togetherform a ring, —(CH₂)₄— is preferred.

In another preferred embodiment the present invention is directed tocompounds of formula

wherein M² is iridium,R¹ is a group of formula

R² is H;

R⁴ is cyclohexyl, F, especially C₁-C₈alkyl, CF₃, or NR⁷R⁹,R⁴″ is C₁-C₈alkyl, or CF₃,R⁷ and R⁹ are independently of each other

orR⁷ and R⁹ together with the nitrogen atom to which they are bonded forma group of formula

R¹⁰ is H, or C₁-C₈alkyl,R³ and R⁸ are C₁-C₈alkyl, —Si(C₁-C₄alkyl)₃, or C₃-C₆cycloalkyl; and

L is

In another preferred embodiment the present invention is directed tocompounds of formula

wherein M² is iridium, R¹ is a group of formula

R⁴ is C₁-C₈alkyl, or CF₃, R⁴″ is C₁-C₈alkyl, R² is H, R³ and R⁸ areC₁-C₈alkyl, —Si(C₁-C₄alkyl)₃, or C₃-C₆cycloalkyl; and L is

In another preferred embodiment the present invention is directed tocompounds of formula

wherein M² is iridium, R¹ is a group of formula

R⁴ is NR⁷R⁹, R⁷ and R⁹ are independently of each other

or R⁷ and R⁹ together with the nitrogen atom to which they are bondedform a group of formula

R¹⁰ is H, or C₁-C₈alkyl, R² is H, R³ and R⁸ are C₁-C₈alkyl,—Si(C₁-C₄alkyl)₃, or C₃-C₆cycloalkyl; and L is

In another preferred embodiment the present invention is directed tocompounds of formula

wherein M² is iridium, R¹ is a group of formula

R⁴ is CF₃, R² is H, R³ and R⁸ are C₁-C₈alkyl, —Si(C₁-C₄alkyl)₃, orC₃-C₆cycloalkyl; and L is

In another preferred embodiment the present invention is directed tocompounds of formula

wherein M² is iridium, R¹ is a group of formula

R^(4′) is H, CF₃ or C₁-C₈alkyl; R² is H, R³ and R⁸ are C₁-C₈alkyl,—Si(C₁-C₄alkyl)₃, or C₃-C₆cycloalkyl; and L is

Most preferred are compounds of formula:

wherein R¹ is C₁-C₅alkyl, especially methyl, ethyl, tert-butyl,iso-butyl, or neopentyl,R³ and R⁸ are C₁-C₅alkyl, especially methyl, ethyl, iso-butyl, orneopentyl and L is

Examples of specific compounds of formula I are compounds A-1 to A-114,B-1 to B-144, C-1 to C-120 and D-1 to D41. Reference is made to claim 9.Compounds, A-1, A-16, A-30, A-44, A-58, A-72, A-87 and A-101, wherein R¹is H, are less preferred.

Special emphasis among them is given to compounds A-9, A-23, A-37, A-2,A-3, A-31, A-10, A-24, A-38, A-65, A-79, A-94, A-59, A-73, A-88, A-66,A-80, A-95, A-12, A-14, A-26, A-28, A-40, A-42, A-54, A-56, A-68, A-70,A-82, A-84, A-97, A-99, A-111, A-113, B-1, B-2, B-3, B-4, B-7, B-9,B-13, B-15, B-17, B-20, B-21, B-22, B-23, B-26, B-27, B-31, B-33, B-35,B-38, B-39, B-40, B-41, B-44, B-45, B-49, B-51, B-53, B-56, B-57, B-58,B-59, B-62, B-63,

B-67, B-69, B-71, B-74, B-75, B-76, B-79, B-80, B-84, B-86, B-88, B-91,B-92, B-93, B-94, B-97, B-98, B-102, B-104, B-106, B-109, B-110, B-111,B-112, B-115, B-116, B-120, B-122, B-124, B-127, B-128, B-129, B-133,B-134, B-138, B-140, B-142, C-2 to C-4, C-6, C-9 to C-12, C-14, C-63 toC-65, C-67, C-69 to C-72, C-74, D-2 to D-4, D-6, D-9 to D-12, and D-14.More preferred compounds are A-9, A-23, A-37, A-2, A-3, A-31, A-10,A-24, A-38, A-65, A-79, A-94, A-59, A-73, A-88, A-66, A-80, A-95, A-12,A-14, A-26, A-28, A-40, A-42, A-54, A-56, A-68, A-70, A-82, A-84, A-97,A-99, A-111, A-113, C-2 to C-4, C-6, C-9 to C-12, C-14, C-63 to C-65,C-67, C-69 to C-72, and C-74. Even more preferred compounds are A-9,A-23, A-37, A-2, A-3, A-31, A-10, A-24, A-38, A-65, A-79, A-94, A-59,A-73, A-88, A-66, A-80, A-95, A-12, A-14, A-26, A-28, A-40, A-42, A-54,A-56, A-68, A-70, A-82, A-84, A-97, A-99, A-111, and A-113. Mostpreferred are compounds of formula:

Cpd. L R¹ R³ R⁸ A-9 A¹⁾ —CH₂CH(CH₃)₂ —CH₃ —CH₃ A-23 A¹⁾ —CH₂CH(CH₃)₂—CH₂CH₃ —CH₂CH₃ A-37 A¹⁾ —CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂ A-2 A¹⁾—CH₃ —CH₃ —CH₃ A-3 A¹⁾ —CH₃ —CH₂CH₃ —CH₂CH₃ A-31 A¹⁾ —CH₃ —CH₂CH(CH₃)₂—CH₂CH(CH₃)₂ A-10 A¹⁾ —C(CH₃)₃ —CH₃ —CH₃ A-24 A¹⁾ —C(CH₃)₃ —CH₂CH₃—CH₂CH₃ A-38 A¹⁾ —C(CH₃)₃ —CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂ A-65 B¹⁾—CH₂CH(CH₃)₂ —CH₃ —CH₃ A-79 B¹⁾ —CH₂CH(CH₃)₂ —CH₂CH₃ —CH₂CH₃ A-94 B¹⁾—CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂ A-59 B¹⁾ —CH₃ —CH₃ —CH₃ A-73 B¹⁾—CH₃ —CH₂CH₃ —CH₂CH₃ A-88 B¹⁾ —CH₃ —CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂ A-66 B¹⁾—C(CH₃)₃ —CH₃ —CH₃ A-80 B¹⁾ —C(CH₃)₃ —CH₂CH₃ —CH₂CH₃ A-95 B¹⁾ —C(CH₃)₃—CH₂CH(CH₃)₂ —CH₂CH(CH₃)₂

The metal complexes of the present invention can be prepared accordingto usual methods known in the prior art. A convenient one-step methodfor preparing iridium metal complexes of formula Ir(L^(a))₃

comprises reacting commercially available iridium trichloride hydratewith an excess of L^(a)H in the presence of 3 equivalents silvertrifluoroacetate and optionally in the presence of a solvent (such ashalogen based solvents, alcohol based solvents, ether based solvents,ester based solvents, ketone based solvents, nitrile based solvents, andwater). The tris-cyclometalated iridium complexes are isolated andpurified by conventional methods. In some cases mixtures of isomers areobtained. Often the mixture can be used without isolating the individualisomers.

The iridium metal complexes of formula Ir(L^(a))₂L can, for example, beprepared by first preparing an intermediate iridium dimer of formula

wherein X is H, methyl, or ethyl, and La is as defined above, and thenaddition of HL. The iridium dimers can generally be prepared by firstreacting iridium trichloride hydrate with HL^(a) and adding NaX and byreacting iridium trichloride hydrate with HL^(a) in a suitable solvent,such as 2-ethoxyethanol. The compounds of formula

are new and form a further aspect of the present invention.

Accordingly, the present invention relates to compounds of formula

wherein X is H, methyl, or ethyl,

La is

wherein R¹, R², R³ and R⁸ are as defined above.

Compounds of formula VIa, or VIb can be synthesized, for example, asoutlined in FIGS. 7 and 8 of U.S. Pat. No. 7,166,368.

C₁-C₁₈alkyl is a branched or unbranched radical such as for examplemethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl,tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl,1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl,1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl,2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl,decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl,tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,icosyl or docosyl. C₁-C₈alkyl is a branched or unbranched radical suchas for example methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl,1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl,1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, or2-ethylhexyl.

C₁-C₈perfluoroalkyl is a branched or unbranched radical, such as, forexample, —CF₃, —CF₂CF₃, -CF₂CF₂CF₃, —CF(CF₃)₂, —(CF₂)₃CF₃, and —C(CF₃)₃.

C₃-C₈cycloalkyl is preferably C₅-C₁₂cycloalkyl or said cycloalkylsubstituted by one, or two C₁-C₈alkyl, or C₁-C₈perfluoroalkyl groups,such as, for example, cyclopropyl, cyclobutyl, cyclopentyl,methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, trimethylcyclohexyl, and tert-butylcyclohexyl.

C₁-C₈alkoxy radicals are straight-chain or branched alkoxy radicals,e.g. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy,tert-butoxy, amyloxy, isoamyloxy or tertamyloxy, heptyloxy, or octyloxy.

Aryl is usually C₆-C₁₈aryl, preferably C₆-C₁₀aryl, which optionally canbe substituted, such as, for example, phenyl, 4-methylphenyl,4-methoxyphenyl, naphthyl, biphenylyl, 2-fluorenyl, phenanthryl,anthryl, tetracenyl, terphenylyl or quadphenylyl; or phenyl substitutedby one to three C₁-C₄alkyl groups, for example o-, m- or p-methylphenyl,2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl,2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl,2-methyl-6-ethylphenyl, 4-tert-butylphenyl, 2-ethylphenyl or2,6-diethylphenyl.

C₇-C₂₄aralkyl radicals are preferably C₇-C₁₅aralkyl radicals, which maybe substituted, such as, for example, benzyl, 2-benzyl-2-propyl,β-phenethyl, α-methylbenzyl, α,α-dimethylbenzyl, ω-phenyl-butyl,ω-phenyl-octyl, ω-phenyl-dodecyl; or phenyl-C₁-C₄alkyl substituted onthe phenyl ring by one to three C₁-C₄alkyl groups, such as, for example,2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2,4-dimethyl benzyl,2,6-dimethylbenzyl or 4-tert-butylbenzyl.or3-methyl-5-(1′,1′,3′,3′-tetramethyl-butyl)-benzyl.

Heteroaryl is typically C2_Cioheteroaryl, i.e. a ring with five to sevenring atoms or a condensed rig system, wherein nitrogen, oxygen or sulfurare the possible hetero atoms, and is typically an unsaturatedheterocyclic radical with five to 12 atoms having at least sixconjugated π-electrons such as thienyl, benzo[b]thienyl,dibenzo[b,d]thienyl, thianthrenyl, fury!, furfuryl, 2H-pyranyl,benzofuranyl, isobenzofuranyl, dibenzofuranyl, phenoxythienyl, pyrrolyl,imidazolyl, pyrazolyl, pyridyl, bipyridyl, triazinyl, pyrimidinyl,pyrazinyl, pyridazinyl, indolizinyl, isoindolyl, indolyl, or indazolyl,which can be unsubstituted or substituted.

Possible substituents of the above-mentioned groups are C₁-C₈alkyl,C₁-C₈alkoxy, fluorine, C₁-C₈perfluoroalkyl, or a cyano group.

The triC₁-C₈alkylsilyl group is preferably a triC₁-C₄alkylsilylgroup,such as, for example, a trimethylsilyl group.

If a substituent, such as, for example, R⁴, R⁵, or R⁶, occurs more thanone time in a group, it can be different in each occurrence.

It has been found that the compounds of the formula I are particularlysuitable for use in applications in which charge carrier conductivity isrequired, especially for use in organic electronics applications, forexample selected from switching elements such as organic transistors,e.g. organic FETs and organic TFTs, organic solar cells and organiclight-emitting diodes (OLEDs), the compounds of the formula I beingparticularly suitable in OLEDs for use as guest material in alight-emitting layer, especially in combination with a host material. Inthe case of use of the inventive compounds of the formula I in OLEDs,OLEDs which have good efficiencies and a long lifetime and which can beoperated especially at a low use and operating voltage are obtained. Theinventive compounds of the formula I are suitable especially for use asemitting materials (phosphorescence emitters).

Suitable structures of organic electronic devices are known to thoseskilled in the art and are specified below.

The organic transistor generally includes a semiconductor layer formedfrom an organic layer with hole transport capacity and/or electrontransport capacity; a gate electrode formed from a conductive layer; andan insulating layer introduced between the semiconductor layer and theconductive layer. A source electrode and a drain electrode are mountedon this arrangement in order thus to produce the transistor element. Inaddition, further layers known to those skilled in the art may bepresent in the organic transistor.

The organic solar cell (photoelectric conversion element) generallycomprises an organic layer present between two plate-type electrodesarranged in parallel. The organic layer may be configured on a comb-typeelectrode. There is no particular restriction regarding the site of theorganic layer and there is no particular restriction regarding thematerial of the electrodes. When, however, plate-type electrodesarranged in parallel are used, at least one electrode is preferablyformed from a transparent electrode, for example an ITO electrode or afluorine-doped tin oxide electrode. The organic layer is formed from twosublayers, i.e. a layer with p-type semiconductor properties or holetransport capacity, and a layer formed with n-type semiconductorproperties or electron transport capacity. In addition, it is possiblefor further layers known to those skilled in the art to be present inthe organic solar cell.

The present invention further provides an organic light-emitting diodecomprising an anode An and a cathode Ka and a light-emitting layer Earranged between the anode An and the cathode Ka, and if appropriate atleast one further layer selected from the group consisting of at leastone blocking layer for holes/excitons, at least one blocking layer forelectrons/excitons, at least one hole injection layer, at least one holetransport layer, at least one electron injection layer and at least oneelectron transport layer, wherein the at least one compound of theformula I is present in the light-emitting layer E and/or in at leastone of the further layers. The at least one compound of the formula I ispreferably present in the light-emitting layer and/or the blocking layerfor holes and/or electron transport layer. For the use of the compoundsof formula I in electronic devices the same preferences with respect tothe compounds of formula I apply as specified above with respect to thecompounds of formula I.

Structure of the Inventive OLED

The inventive organic light-emitting diode (OLED) thus generally has thefollowing - structure:

an anode (An) and a cathode (Ka) and a light-emitting layer E arrangedbetween the anode (An) and the cathode (Ka).

The inventive OLED may, for example—in a preferred embodiment—be formedfrom the following layers:

-   1. Anode-   2. Hole transport (conductor) layer-   3. Light-emitting layer-   4. Blocking layer for holes/excitons-   5. Electron transport (conductor) layer-   6. Cathode

Layer sequences different than the aforementioned structure are alsopossible, and are known to those skilled in the art. For example, it ispossible that the OLED does not have all of the layers mentioned; forexample, an OLED with layers (1) (anode), (3) (light-emitting layer) and(6) (cathode) is likewise suitable, in which case the functions of thelayers (2) (hole conductor layer) and (4) (blocking layer forholes/excitons) and (5) (electron conductor layer) are assumed by theadjacent layers. OLEDs which have layers (1), (2), (3) and (6), orlayers (1), (3), (4), (5) and (6), are likewise suitable. In addition,the OLEDs may have a blocking layer for electrons/excitons between theanode (1) and the hole conductor layer (2).

It is additionally possible that a plurality of the aforementionedfunctions (electron/exciton blocker, hole/exciton blocker, holeinjection, hole conduction, electron injection, electron conduction) arecombined in one layer and are assumed, for example, by a single materialpresent in this layer. For example, a material used in the holeconductor layer, in one embodiment, may simultaneously block excitonsand/or electrons.

Furthermore, the individual layers of the OLED among those specifiedabove may in turn be formed from two or more layers. For example, thehole conductor layer may be formed from a layer into which holes areinjected from the electrode, and a layer which transports the holes awayfrom the hole-injecting layer into the light-emitting layer. Theelectron conduction layer may likewise consist of a plurality of layers,for example a layer in which electrons are injected by the electrode,and a layer which receives electrons from the electron injection layerand transports them into the light-emitting layer.

In order to obtain particularly efficient OLEDs, for example, the HOMO(highest occupied molecular orbital) of the hole transport layer shouldbe matched to the work function of the anode, and the LUMO (lowestunoccupied molecular orbital) of the electron transport layer should bematched to the work function of the cathode, provided that theaforementioned layers are present in the inventive OLEDs.

The anode (1) is an electrode which provides positive charge carriers.It may be formed, for example, from materials which comprise a metal, amixture of various metals, a metal alloy, a metal oxide or a mixture ofvarious metal oxides. Alternatively, the anode may be a conductivepolymer. Suitable metals comprise metals and alloys of the metals of themain groups, transition metals and of the lanthanoids, especially themetals of groups Ib, IVa, Va and VIa of the periodic table of theelements, and the transition metals of group VIIIa. When the anode is tobe transparent, generally mixed metal oxides of groups IIb, IIIb and IVbof the periodic table of the elements (IUPAC version) are used, forexample indium tin oxide (ITO). It is likewise possible that the anode(1) comprises an organic material, for example polyaniline, asdescribed, for example, in Nature, Vol. 357, pages 477 to 479 (Jun. 11,1992). At least either the anode or the cathode should be at leastpartly transparent in order to be able to emit the light formed. Thematerial used for the anode (1) is preferably ITO.

Suitable hole transport materials for layer (2) of the inventive OLEDsare disclosed, for example, in Kirk-Othmer Encyclopedia of ChemicalTechnology, 4th edition, Vol. 18, pages 837 to 860, 1996. Bothhole-transporting molecules and polymers can be used as the holetransport material. Hole-transporting molecules typically used areselected from the group consisting oftris[N-(1-naphthyl)-N-(phenylamino)]triphenylamine (1-NaphDATA),4,4′-bis [N-(1-naphthyl)-N-phenylamino]piphenyl (α-NPD),N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1, 1′-biphenyl]-4,4%-diamine(TPD), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)[1,1′-(3,3′,-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),α-phenyl-4-N, N-diphenylaminostyrene (TPS), p-(diethylamino)benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),bis[4-(N,N-diethylamino)-2-methylphenyl)(4-methylphenyl)methane (MPMP),1-phenyl-3[p-(diethylamino)styryl]-54p-(diethylamino)phenyl]pyrazoline(PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB),N,N,N′,N′-tetrakis (4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TTB),4,4′,4″-tris(N, N-diphenylamino)triphenylamine (TDTA),4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-bis(naphthalen-2-yl)-N,N′-bis(phenyl)benzidine (13-NPB),N,N′-bis(3-methylphenyl)-N, N′-bis(phenyl)-9,9-spirobifluorene(Spiro-TPD), N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-spirobifluorene (Spiro-NPB),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9, 9-dimethylfluorene(DMFL-TPD), di[4-(N,N-ditolylamino)phenyl]cyclohexane, N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-dimethylfluorene,N,N′-bis(naphthalen-1-yl)-N, N′-bis(phenyl)-2,2-dimethylbenzidine,N,N^(.)-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine,N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine,2,3,5,6-tetrafluoro-7,7,8, 8-tetracyanoquinodimethane (F4-TCNQ),4,4′,4″-tris(N-3-methylphenyl-N- phenylamino)triphenylamine,4,4′,4″-tris(N-(2-naphthyl)-N-phenyl-amino)triphenylamine,pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile (PPDN),N,N,N′,N′-tetrakis (4-methoxyphenyl)benzidine (MeO-TPD), 2,7-bis[N,N-bis(4-methoxyphenyl)amino]-9, 9-spirobifluorene(MeO-Spiro-TPD), 2,2′-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene (2,2′-MeO-Spiro-TPD), N,N′-diphenyl-N,N′-di[4-(N,N-ditolylamino)phenyl]benzidine (NTNPB), N,N′-diphenyl-N,N′-di[4-(N,N-diphenylamino)phenyl]benzidine (NPNPB),N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1, 4-diamine (β-NPP),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-diphenylfluorene(DPFL-TPD),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-diphenylfluorene(DPFL-NPB), 2,2′,7,7′-tetrakis(N,N-diphenylamino)-9,9′-spirobifluorene(Spiro-TAD), 9,9-bis[4-(N, N-bis(biphenyl-4-yl)amino)phenyl]-9H-fluorene(BPAPF), 9,9-bis[4-(N,N-bis (naphthalen-2-yl)amino)phenyl]-9H-fluorene(NPAPF), 9,9-bis[4-(N,N-bis(naphthalen-2-yl)-N,N′-bisphenylamino)phenyl]-9H-fluorene (NPBAPF),2,2′,7,7′-tetrakis[N-naphthalenyl (phenyl)amino]-9,9′-spirobifluorene(Spiro-2NPB), N,N′-bis(phenanthren-9-yl)-N, N′-bis(phenyl)benzidine(PAPB), 2,7-bis[N,N-bis(9,9-spirobifluoren-2-yl)amino]-9,9-spirobifluorene (Spiro-5),2,2′-bis[N,N-bis(biphenyl-4-yl)amino]9,9-spirobifluorene (2,2′-Spiro-DBP), 2,2′-bis(N,N-diphenylamino)-9.9-spirobifluorene(Spiro-BPA), 2,2′,7, 7′-tetra(N,N-ditolyl)aminospirobifluorene(Spiro-TTB), N,N,N′,N′-tetranaphthalen-2-ylbenzidine (TNB), porphyrincompounds and phthalocyanines such as copper phthalocyanines andtitanium oxide phthalocyanines. Hole-transporting polymers typicallyused are selected from the group consisting of polyvinylcarbazoles,(phenylmethyl)polysilanes and polyanilines. It is likewise possible toobtain hole-transporting polymers by doping hole-transporting moleculesinto polymers such as polystyrene and polycarbonate. Suitablehole-transporting molecules are the molecules already mentioned above.

In addition—in one embodiment—it is possible to use carbene complexes ashole transport materials, the band gap of the at least one holetransport material generally being greater than the band gap of theemitter material used. In the context of the present application, “bandgap” is understood to mean the triplet energy. Suitable carbenecomplexes are, for example, carbene complexes as described in WO2005/019373 A2, WO 2006/056418 A2, WO2005/113704, WO 2007/115970,WO2007/115981 and WO2008/000727. One example of a suitable carbenecomplex is Ir(dpbic)₃ with the formula:

which is disclosed, for example, in WO2005/019373. In principle, it ispossible that the hole transport layer comprises at least one compoundof the formula I as hole transport material.

The light-emitting layer (3) includes a compound of formula I accordingto the present invention (emitter).

The light-emitting layer (3) may comprise a host material. Suitable hostmaterials are, for example, described in EP2363398A1, WO2008031743,WO2008065975, WO2010145991, WO2010047707, US20090283757, US20090322217,US20100001638, WO2010002850, US20100060154, US20100060155,US20100076201, US20100096981, US20100156957, US2011186825, US2011198574,US20110210316, US2011215714, US2011284835, and PCT/EP2011/067255. Thehost material may be an organic compound having hole-transportingproperty and/or an organic compound having electron-transportingproperty. Preferably, the light-emitting layer (3) comprises a compoundof formula I according to the present invention and an organic compoundhaving hole-transporting property; or the light-emitting layer (3)comprises a compound of formula I according to the present invention, anorganic compound having hole-transporting property and an organiccompound having electron-transporting property.

The compound of formula I is used in the emitting layer (3) in an amountof 0.01 to 15% by weight, preferably 1 to 10% by weight based on theamount of the compound of formula I, the organic compound havinghole-transporting property and/or the organic compound havingelectron-transporting property. Furthermore, the weight ratio of theorganic compound having hole-transporting property to the organiccompound having electron-transporting property is preferably in therange of 1:20 to 20:1. For the compound of formula I the samepreferences apply as specified above.

In principle, any organic compound having hole-transporting property canbe used as host in the emitting layer. Examples of organic compoundshaving a hole transport property which can be used for the host materialinclude an aromatic amine compound such as 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD), 4,4′-bis[N-(naphthyl)-N-phenylamino]piphenyl (=NPB), 4,4′-bis[N-(9-phenanthryl)-N-phenylamino]biphenyl (=PPB), 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (=TPD), 4, 4′-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl (=DFLDPBi), 4, 4,4″-tris(N, N-diphenyl-amino)-triphenylamine (=TDATA), 4, 4,4″-tris[N-(3-methylphenyl)-N-phenylamino ]-triphenylamine (=m-MTDATA),4,4, 4″-tris-(N-carbazolyl)triphenylamine (=TCTA), 1,1-bis[4-(diphenylamino)phenyl]-cyclohexane (=TPAC),9,9-bis[4-(diphenylamino)phenyl ]-fluorene (=TPAF),N44-(9-carbazolyl)phenyll-N-phenyl-9, 9-dinnethylfluoren-2-amine(abbreviation: YGAF) and a carbazole derivative such as 4,4′-di(carbazolyl)biphenyl (abbreviation: CBP),1,3-bis(carbazolyl)benzene (abbreviation: mCP) or 1,3,5-tris(N-carbazolyl)benzene (abbreviation: TCzB), =DNTPD,

Examples of high molecular compounds having a hole-transport propertywhich can be used for the host material include poly(N-vinylcarbazole)(=PVK), poly(4-vinyltriphenyl-amine) (=PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}-phenyl)methacrylamide] (=PTP-DMA),poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)-benzidine (=Poly-TPD), andthe like.

In principle, any organic compound having electron-transporting propertycan be used as host in the emitting layer. Examples of organic compoundshaving an electron transport property which can be used for the hostmaterial include a heteroaromatic compound such as9-[4-(5-phenyl-1,3,4-oxadiazo1-2-yl)phenyl]carbazole, 1,3-bis[5-(p-tert-butylphenyl)-1, 3,4-oxadiazol-2-yl]benzene (=OXD-7),2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3, 4-oxadiazole (=PBD),2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (=TPBI),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (=TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(=p-EtTAZ), 9,9′,9″-[1,3, 5-triazine-2,4,6-triyl]tricarbazole (=TCzTRZ), 2,2′,2″-(1,3,5-benzenetriyl)tris(6,7-dimethyl-3-phenylquinoxaline) (=TriMeQn),2,3-bis(4-diphenylaminophenyl)quinoxaline (=TPAQn),9,9′-(quinoxaline-2,3-diyldi-4,1-phenylene)di(9H-carbazole) (=CzQn),3,3′,6, 6′-tetraphenyl-9,9′-(quinoxaline-2, 3-diyldi-4,1-phenylene)di(9H-carbazole) (=DCzPQ), bathophenanthro-line (=BPhen), orbathocuproine (=BCP), and a metal complex such as tris(8-quinolinolato)aluminum (=Alq₃), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (=BAlq), tris[2(2-hydroxyphenyl)-5-phenyl-1,3, 4-oxadiazolato]aluminum(III)(=Al(OXD)₃), tris(2-hydroxyphenyl-1-phenyl-1-H-benzimidazolato)aluminum(III) (=Al(BIZ)₃),bis[2-(2-hydroxyphenyl)benzothiazolato]zinc(II) (=Zn(BTZ)₂),bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(II) (=Zn(PBO)2),bis[2-(2-hydroxyphenyl)pyridinato]zinc (=Znpp2),

Examples of high molecular compounds having an electron-transportproperty which can be used for the host material include poly(2,5-pyridinediyl) (abbreviation: PPy), poly [(9, 9-dihexylfluorene-2,7-diyl)-co-(pyridine-3, 5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctylfluorene-2, 7-diyl)-co-(2, 2′-bipyridine-6, 6′-diyl)](abbreviation: PF-BPy), and the like.

In another embodiment of the present invention bipolar host materials,such as, for example,

can be used.

The light-emitting layer may comprise further components in addition tothe emitter material. For example, a fluroescent dye may be present inthe light-emitting layer in order to alter the emission color of theemitter material. In addition—in a preferred embodiment—a matrixmaterial can be used. This matrix material may be a polymer, for examplepoly(N-vinylcarbazole) or polysilane. The matrix material may, however,be a small molecule, for example 4,4′-N,N′-dicarbazolebiphenyl (CDP=CBP)or tertiary aromatic amines, for example TCTA. In a preferred embodimentof the present invention, at least one compound of the formula 1 is usedas matrix material.

A blocking layer for holes may be present. Examples of hole blockermaterials typically used in OLEDs are 2,6-bis(N-carbazolyl)pyridine(mCPy), 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline (bathocuproin,(BCP)), bis(2-methyl-8-quinolinato)-4-phenyl-phenylato) aluminum(III)(BAlq), phenothiazine S,S-dioxide derivates and 1,3,5-tris(N-phenyl-2-benzylimidazolyl)benzene) (TPBI), TPBI also being suitableas electron-conducting material. Further suitable hole blockers and/orelectron transport materials are2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1-H-benzimidazole),2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1, 3,4-oxadiazole,8-hydroxyquinolinolatolithium, 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole,1,3-bis[2-(2,2′-bipyridin-6-yl)1,3,4-oxadiazo-5-yl]benzene,4,7-diphenyl-1,10-phenanthroline,3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole,6,6′-bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2′-bipyridyl,2-phenyl-9,10-di (naphthalene-2-yl)anthracene,2,7-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluorene,1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene,2-(naphthalene-2-yl)-4, 7-di-phenyl-1,10-phenanthroline,tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane, 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline,1-methyl-2-(4-(naphthalene2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline. In a further embodiment,it is possible to use compounds which comprise aromatic orheteroaromatic rings joined via groups comprising carbonyl groups, asdisclosed in WO2006/100298, disilyl compounds selected from the groupconsisting of disilylcarbazoles, disilylbenzofurans,disilylbenzothiophenes, disilylbenzophospholes, disilylbenzothiopheneS-oxides and disilylbenzothiophene S,S-dioxides, as specified, forexample, in PCT applications WO2009003919 and WO2009003898, which wereyet to be published at the priority date of the present application, anddisilyl compounds as disclosed in WO2008/034758, as a blocking layer forholes/excitons (4) or as matrix materials in the light-emitting layer(3).

Suitable electron transport materials for the layer (5) of the inventiveOLEDs comprise metals chelated to oxinoid compounds, such as2,2′,2″-(1,3,5-phenylene)tris [1-phenyl-1H-benzimidazole] (TPBI),tris(8-quinolinolato)aluminum (Alq₃), compounds based on phenanthroline,such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA=BCP) or 4,7-diphenyl-1,10-phenanthroline (DPA), and azole compounds such as2-(4-biphenylyl)-5-(4-t-butylphenyl)-1, 3,4-oxadiazole (PBD) and3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1, 2,4-triazole (TAZ),8-hydroxyquinolinolatolithium (Liq), 4,7-diphenyl-1,10-phenanthroline(BPhen), bis(2-methyl-8-quinolinolato)-4-(phenylphenolato)aluminum(BAlq), 1,3-bis[2-(2, 2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]benzene(Bpy-OXD), 6,6′-bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2′-bipyridyl (BP-OXD-Bpy),4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2, 4-triazole (NTAZ),2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (NBphen), 2,7-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluorene(Bby-FOXD), 1, 3-bis[2-(4-tertbutylphenyl)-1,3,4-oxadiazo-5-yl]benzene(OXD-7), tris(2,4,6-trimethyl-3-(pyridin-3-yl) phenyl)borane (3TPYMB),1-methyl-2-(4-(naphthalen-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (2-NPIP),2-phenyl-9,10-di(naphthalen-2-yl)anthracene (PADN),2-(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (HNBphen). Thelayer (5) may serve both to facilitate electron transport and as abuffer layer or barrier layer in order to prevent quenching of theexciton at the interfaces of the layers of the OLED. The layer (5)preferably improves the mobility of the electrons and reduces quenchingof the exciton. In a preferred embodiment, BCP is used as the electrontransport material. In another preferred embodiment, the electrontransport layer comprises at least one compound of the formula 1 aselectron transport material.

Among the materials mentioned above as hole transport materials andelectron transport materials, some may fulfil several functions. Forexample, some of the electron-conducting materials are simultaneouslyhole-blocking materials when they have a low-lying HOMO. These can beused, for example, in the blocking layer for holes/excitons (4).However, it is likewise possible that the function as a hole/excitonblocker is also adopted by the layer (5), such that the layer (4) can bedispensed with.

The charge transport layers can also be electronically doped in order toimprove the transport properties of the materials used, in order firstlyto make the layer thicknesses more generous (avoidance of pinholes/shortcircuits) and in order secondly to minimize the operating voltage of thedevice. For example, the hole transport materials can be doped can bedoped with tetrafluorotetracyanquinodimethane (F4-TCNQ) or with MoO₃ orWO₃. The electron transport materials can be doped, for example, withalkali metals, for example Alq₃ with lithium. In addition, electrontransports can be doped with salts such as Cs₂CO₃, or8-hydroxyquinolato-lithium (Liq). Electronic doping is known to thoseskilled in the art and is disclosed, for example, in W. Gao, A. Kahn, J.Appl. Phys., Vol. 94, No. 1, 1 Jul. 2003 (p-doped organic layers); A. G.Werner, F. Li, K. Harada, M. Pfeiffer, T. Fritz, K. Leo. Appl. Phys.Lett., Vol. 82, No. 25, 23 Jun. 2003 and Pfeiffer et al., OrganicElectronics 2003, 4, 89-103. For example, the hole transport layer may,in addition to a carbene complex, e.g. Ir(dpbic)₃, be doped with MoO₃ orWO₃. For example, the electron transport layer may comprise BCP dopedwith Cs₂CO₃.

The cathode (6) is an electrode which serves to introduce electrons ornegative charge carriers. Suitable materials for the cathode areselected from the group consisting of alkali metals of group Ia, forexample Li, Cs, alkaline earth metals of group Ila, for example calcium,barium or magnesium, metals of group IIb of the periodic table of theelements (old IUPAC version), comprising the lanthanides and actinides,for example samarium. In addition, it is also possible to use metalssuch as aluminum or indium, and combinations of all metals mentioned. Inaddition, alkali metal-comprising organometallic compounds, or alkalimetal fluorides, such as, for example, LiF, CsF, or KF, can be appliedbetween the organic layer and the cathode in order to reduce theoperating voltage.

The OLED according to the present invention may additionally comprisefurther layers which are known to those skilled in the art. For example,a layer which facilitates the transport of the positive charge and/ormatches the band gaps of the layers to one another may be appliedbetween the layer (2) and the light-emitting layer (3). Alternatively,this further layer may serve as a protective layer. In an analogousmanner, additional layers may be present between the light-emittinglayer (3) and the layer (4) in order to facilitate the transport ofnegative charge and/or to match the band gaps between the layers to oneanother. Alternatively, this layer may serve as a protective layer.

In a preferred embodiment, the inventive OLED, in addition to layers (1)to (6), comprises at least one of the following layers mentioned below:

-   -   a hole injection layer between the anode (1) and the        hole-transporting layer (2) having a thickness of 2 to 100 nm,        preferably 5 to 50 nm;    -   a blocking layer for electrons between the hole-transporting        layer (2) and the light-emitting layer (3);    -   an electron injection layer between the electron-transporting        layer (5) and the cathode (6).

Materials for a hole injection layer may be selected from copperphthalocyanine, 4,4′,4″-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA),4,4′,4″-tris (N-(2-naphthyl)-N-phenylamino)triphenylamine (2T-NATA),4,4′,4″-tris(N-(1-naphthyl)-N-phenylamino) triphenylamine (1T-NATA),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (NATA), titanium oxidephthalocyanine, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquino-dimethane(F4-TCNQ), pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile(PPDN), N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD),2,7-bis[N,N-bis(4-methoxy-phenyl) amino]-9,9-spirobifluorene(MeO-Spiro-TPD), 2,2′-bis[N,N-bis(4-methoxy-phenyl)amino]-9,9-spirobifluorene (2,2′-MeO-Spiro-TPD), N,N′-diphenyl-N,N′-di-[4-(N, N-ditolylamino)phenyl]benzidine (NTNPB),N,N′-diphenyl-N ,N-di-[4-(N, N-diphenyl-amino)phenyl]benzidine (NPNPB),N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1, 4-diamine (α-NPP). Inprinciple, it is possible that the hole injection layer comprises atleast one compound of the formula I as hole injection material. Inaddition, polymeric hole-injection materials can be used such aspoly(N-vinylcarbazole) (PVK), polythiophenes, polypyrrole, polyaniline,self-doping polymers, such as, for example, sulfonatedpoly(thiophene-3[2[(2-methoxyethoxy)ethoxy]-2,5-diyl) (Plexcore³ OCConducting Inks commercially available from Plextronics), and copolymerssuch as poly(3, 4-ethylenedioxythiophene)/poly(4-styrenesulfonate) alsocalled PEDOT/PSS.

As a material for the electron injection layer, LiF, for example, can beselected.

In addition, it is possible that some of the layers used in theinventive OLED have been surface-treated in order to increase theefficiency of charge carrier transport.

The inventive OLED can be produced by methods known to those skilled inthe art. In general, the inventive OLED is produced by successive vapordeposition of the individual layers onto a suitable substrate. Suitablesubstrates are, for example, glass, inorganic semi-conductors or polymerfilms. For vapor deposition, it is possible to use customary techniques,such as thermal evaporation, chemical vapor deposition (CVD), physicalvapor deposition (PVD) and others. In an alternative process, theorganic layers of the OLED can be applied from solutions or dispersionsin suitable solvents, employing coating techniques known to thoseskilled in the art.

In general, the different layers have the following thicknesses: anode(1) 50 to 500 nm, preferably 100 to 200 nm; hole-conducting layer (2) 5to 100 nm, preferably 20 to 80 nm, light-emitting layer (3) 1 to 100 nm,preferably 10 to 80 nm, blocking layer for holes/excitons (4) 2 to 100nm, preferably 5 to 50 nm, electron-conducting layer (5) 5 to 100 nm,preferably 20 to 80 nm, cathode (6) 20 to 1000 nm, preferably 30 to 500nm. The relative position of the recombination zone of holes andelectrons in the inventive OLED in relation to the cathode and hence theemission spectrum of the OLED can be influenced, among other factors, bythe relative thickness of each layer. This means that the thickness ofthe electron transport layer should preferably be selected such that theposition of the recombination zone is matched to the optical resonatorproperty of the diode and hence to the emission wavelength of theemitter. The ratio of the layer thicknesses of the individual layers inthe OLED depends on the materials used. It is possible that theelectron-conducting layer and/or the hole-conducting layer have greaterthicknesses than the layer thicknesses specified when they areelectrically doped.

Use of the compounds of the formula I in at least one layer of the OLED,preferably in the light-emitting layer (preferably as an emittermaterial) makes it possible to obtain OLEDs with high efficiency andwith low use and operating voltage. Frequently, the OLEDs obtained bythe use of the compounds of the formula I additionally have highlifetimes. The efficiency of the OLEDs can additionally be improved byoptimizing the other layers of the OLEDs. For example, high-efficiencycathodes such as Ca or Ba, if appropriate in combination with anintermediate layer of LiF, can be used. Shaped substrates andhole-transporting materials which bring about a reduction in theoperating voltage or an increase in the quantum efficiency are likewiseusable in the inventive OLEDs. Moreover, additional layers may bepresent in the OLEDs in order to adjust the energy level of thedifferent layers and to facilitate electroluminescence.

The OLEDs may further comprise at least one second light-emitting layer.The overall emission of the OLEDs may be composed of the emission of theat least two light-emitting layers and may also comprise white light.

The OLEDs can be used in all apparatus in which electroluminescence isuseful. Suitable devices are preferably selected from stationary andmobile visual display units and illumination units. Stationary visualdisplay units are, for example, visual display units of computers,televisions, visual display units in printers, kitchen appliances andadvertising panels, illuminations and information panels. Mobile visualdisplay units are, for example, visual display units in cellphones,laptops, digital cameras, MP3 players, vehicles and destination displayson buses and trains. Further devices in which the inventive OLEDs can beused are, for example, keyboards; items of clothing; furniture;wallpaper.

In addition, the present invention relates to a device selected from thegroup consisting of stationary visual display units such as visualdisplay units of computers, televisions, visual display units inprinters, kitchen appliances and advertising panels, illuminations,information panels, and mobile visual display units such as visualdisplay units in cellphones, laptops, digital cameras, MP3 players,vehicles and destination displays on buses and trains; illuminationunits; keyboards; items of clothing; furniture; wallpaper, comprising atleast one inventive organic light-emitting diode or at least oneinventive light-emitting layer.

The following examples illustrate certain features and advantages of thepresent invention. They are intended to be illustrative of theinvention, but not limiting. All percentages are by weight, unlessotherwise indicated.

EXAMPLES Ligand Example 1

a) 104 g (0.50 mol) of 9,10-dioxophenanthrene are suspended undernitrogen in 2000 ml of sulfuric acid and treated in small portions witha total of 182.5 g (1.03 mol) of N-bromosuccinimide during one hour at atemperature below 40° C. The resulting red brown viscous reaction massis stirred at room temperature for four hours. The reaction mixture isslowly dropped into 6000 ml of an ice-water mixture under slow stirring.The resulting orange suspension is filtered and the solid washed with5000 ml of water and 2000 ml of ethanol, and then dried under vacuum at70° C. The orange solid is dissolved in 2100 ml N, N-dimethylformamide(DMF) under reflux and further stirred at 80° C. for one hour. Theresulting suspension is filtered at 80° C. and the solid washed with1000 ml of DMF and 600 ml of methanol, followed by drying under vacuumat 80° C., giving the title product as a red powder (yield: 96.8 g(53%)). Melting point: 284-285° C.

b) 7.9 g (0.11 mol) of 1,2-diaminopropane are added under nitrogen to32.6 g (0.09 mol) of 2,7-dibromo-9,10-phenanthrenedione in 2000 ml oftoluene. The red suspension is heated under reflux for 2 h using a waterseparator. The resulting brownish suspension is treated with 40 g ofmanganese(IV)oxide at 94° C., and heating continued under reflux untilno intermediate product is visible anymore on the TLC. The hot blacksuspension is filtered through silica gel (5 cm layer) using a preheatedfunnel, and the silica gel layer rinsed with 800 ml of hot toluene. Asolid immediately precipitates out from the filtrate and is furtherwashed with a small amount of toluene, followed by drying in a vacuumoven, giving the title product as a white solid (yield: 27.7 g (77%)).

c) 11.1 g (27.6 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]guinoxaline(product of Ligand Example 1b), and 4.97 g (83 mmol) of methylboronicacid are suspended under argon in 70 ml of dioxane and 200 ml oftoluene. 0.12 g (0.53 mmol) of palladium(II) acetate and 1.36 g (3.3mmol) of 2-dicyclohexyl-phosphino-2′,6′-dimethoxybiphenyl are added, andthe reaction mixture is degassed with argon. A degassed solution of 63.6g (0.28 mol) of potassium phosphate hydrate in 70 ml of water is added.The yellow suspension is heated under reflux for five hours. Theresulting grey emulsion is filtered through Hyflo and the filter cakewashed with toluene. The organic phase is separated, further washedthree times with 200 ml of water, and concentrated under vacuum. Theresulting solid is recrystallized three times from ethanol providing thetitle product as light white solid (yield: 1.9 g (25%)). Melting point:176-178° C. ¹H-NMR (400 MHz, CDCl₃): δ=2.64 (s, 3 H), 2.65 (s, 3 H),2.86 (s, 3 H), 7.55-7.62 (m, 2 H), 8.47 (d, 2 H), 8.76 (s, 1 H), 8.95(s, 1 H), 9.02 (s, 1 H).

Ligand Example 2

6.03 g (15.0 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]guinoxaline(product of Ligand Example 1b), and 4.58 g (44.9 mmol) of(2-methylpropyl)boronic acid are suspended under argon in 200 ml oftoluene. 0.13 g (0.58 mmol) of palladium(II) acetate and 0.74 g (1.8mmol) of 2-dicyclohexyl-phosphino-2′,6′-dinnethoxybiphenyl are added,followed by the addition of 34.5 g (0.15 mol) of potassium phosphatehydrate. The reaction mixture is degassed with argon and the lightyellow suspension heated under reflux for three hours. The hot greysuspension is filtered through silica gel (2 cm layer), and the silicagel layer rinsed with toluene. The collected eluents are concentratedunder vacuum and the resulting solid recrystallized from ethanol, givingthe title product as a white solid (yield: 4.3 g (80.4%)). Meltingpoint: 129-130° C. ¹H-NMR (300 MHz, CDCl₃): δ=0.98 (d, 6 H), 1.00 (d, 6H), 1.99-2.17 (m, 2 H), 2.76 (dd, 4 H), 2.84 (s, 3 H), 7.52-7.59 (m, 2H), 8.50 (d, 2 H), 8.76 (s, 1 H), 8.92 (d, 1 H), 9.00 (d, 1 H).

Ligand Example 3

The title product is prepared according to the procedure of LigandExample 2, with 6,11-dibromo-2-methyldibenzo[f,h]quinoxaline (product ofLigand Example 1b), giving the title product as a white solid afterrecrystallization from ethanol.

Ligand Example 4

a) 13.7 g (0.12 mol) of 1,2-diaminocyclohexane are added under nitrogento 36.6 g (0.10 mol) of 2,7-dibromo-9,10-phenanthrenedione in 1000 ml oftoluene. The red suspension is heated under reflux for one hour using awater separator. The resulting brownish suspension is diluted by theaddition of 1000 ml toluene and treated with 75 g of manganese(IV)oxideat 84° C., and heating continued under reflux until no intermediateproduct is visible anymore on the TLC. The hot black suspension isfiltered through silica gel (5 cm layer) using a preheated funnel, andthe silica gel layer rinsed with 500 ml of hot toluene. The combinedfiltrates are concentrated and the resulting solid dried under vacuum,giving the title product as a white solid (yield: 42.3 g (96%)). Meltingpoint: 253-254° C. ¹H-NMR (400 MHz, CDCl₃): δ=2.07-2.15 (m, 4 H),3.15-3.26 (m, 4 H), 7.74 (dd, 2 H), 8.22 (d, 2 H), 9.15 (d, 2 H).

b) 6.63 g (15.0 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]quinoxaline(product of Ligand Example 4a), and 4.58 g (44.9 mmol) of(2-methylpropyl)boronic acid are suspended under argon in 200 ml oftoluene. 0.13 g (0.58 mmol) of palladium(II) acetate and 0.74 g (1.8mmol) of 2-dicyclohexyl-phosphino-2′,6′-dinnethoxybiphenyl are added,followed by the addition of 34.5 g (0.15 mol) of potassium phosphatehydrate. The reaction mixture is degassed with argon and the lightyellow suspension heated under reflux for two hours. The hot greysuspension is filtered through silica gel (2 cm layer), and the silicagel layer rinsed with toluene. The collected eluents are concentratedunder vacuum and the resulting solid recrystallized from ethanol, givingthe title product as a white solid (yield: 4.3 g (72%)). Melting point:211-212° C. ¹H-NMR (300 MHz, CDCl₃): δ=0.99 (d, 12 H), 1.99-2.16 (m, 6H), 2.75 (d, 4 H), 3.17-3.28 (m, 4 H), 7.51 (dd, 2 H), 8.47 (d, 2 H),8.93 (d, 2 H).

Liaand Example 5

a) 25.0 g (0.19 mol) of leucinannide (H-Leu-NH2) is added in smallportions under a nitrogen stream at room temperature to a suspension of16.0 g (0.42 mol) of lithium aluminium - hydride in 250 ml of anhydrousTHF. The temperature is slowly increased up to reflux and stirringcontinued for eight hours. The grey suspension is cooled down to roomtemperature, 30 ml of water are slowly added, the suspension filteredthrough Hyflo, followed by extensive washing of Hylo with THF. Thecombined filtrates are concentrated giving 18.4 g of crude product.Further distillation provided a pure fraction of the title product at atemperature of 86-95° C. at 50 mbar, as a colourless oil (12.1 g (54%)).¹H-NMR (300 MHz, CDCl₃): δ=0.90 (d, 3H), 0.93 (d, 3 H), 1.18-1.22 (m, 2H), 1.38 (br. s, 4 H), 1.69-1.79 (m, 1 H), 2.38-2.48 (m, 1 H), 2.67-2.79(m, 2 H).

b) 6.4 g (55 mmol) of the product of Ligand Example 5a are added undernitrogen to 36.6 g (50 mmol) of 2,7-dibromo-9,10-phenanthrenedione in100 ml of toluene. The orange-red suspension is heated under reflux fortwo hours using a water separator. The resulting orange-yellow istreated with 20 g of manganese(IV)oxide at 95° C., and heating continuedunder reflux until no intermediate product is visible anymore on theTLC. The hot black suspension is filtered through Hyflo (5 cm layer)using a preheated funnel, and the Hyflo layer rinsed with hot toluene.The filtrate is cooled down to room temperature and the solid filteredoff, giving a first fraction of 12.1 g of a white solid. The filtrate isconcentrated giving an additional 10.2 g of a white solid. The two solidfractions are combined and suspended in hot toluene, followed byfiltration at room temperature giving the title product as a white solid(yield: 12.4 g (56%)). Melting point: 217-218° C. ¹H-NMR (300 MHz,CDCl₃): δ=1.06 (d, 6 H), 2.28-2.49 (m, 1 H), 2.96 (d, 2 H), 7.81-7.87(m, 2 H), 8.38 (dd, 2 H), 8.74 (s, 1 H), 9.29 (d, 1 H), 9.35 (d, 1 H).

c) 3.7 g (8.3 mmol) of the product of Ligand Example 5b), and 1.5 g(25.1 mmol) of (2-methylpropyl)boronic acid are suspended under argon in150 ml of toluene. 74 mg (0.33 mmol) of palladium(II) acetate and 0.37 g(0.90 mmol) of 2-dicyclohexyl-phosphino-2′, 6′-dimethoxybiphenyl areadded, followed by the addition of 19.2 g (83.4 mmol) of potassiumphosphate hydrate. The reaction mixture is degassed with argon and thelight yellow suspension heated under reflux for 27 h. The hot greysuspension is filtered through silica gel (2 cm layer), and the silicagel layer rinsed with toluene. The collected eluents are concentratedunder vacuum and the resulting solid recrystallized from ethanol, givingthe title product as a white solid (yield: 2.2 g (71%)). Melting point:211-212° C.

Ligand Example 6

4.4 g (8.3 mmol) of the product of Ligand Example lb), and 3.06 g (30.0mmol) of (2-methylpropyl)boronic acid are suspended under argon in 150ml of toluene. 90 mg (0.40 mmol) of palladium(II) acetate and 0.5 g(1.22 mmol) of 2-dicyclohexyl-phosphino-2′, 6′-dimethoxybiphenyl areadded, followed by the addition of 23 g (99.9 mmol) of potassiumphosphate hydrate. The reaction mixture is degassed with argon and thelight yellow suspension heated under reflux for three hours. The hotgrey suspension is filtered through silica gel (2 cm layer), and thesilica gel layer rinsed with toluene. The collected eluents areconcentrated under vacuum and the resulting solid recrystallized fromethanol, giving the title product as a white solid (yield: 2.9 g (73%)).Melting point: 129-130° C. ¹H-NMR (300 MHz, CDCl₃): δ=0.99 (d, 6 H),1.00 (d, 6 H), 1.06 (d, 6 H), 2.00-2.16 (m, 2 H), 2.29-2.44 (m, 1 H),2.76 (dd, 4 H), 2.96 (d, 2 H), 7.52-7.59 (m, 2 H), 7.00 (d, 2 H), 8.71(s, 1 H), 8.93 (d, 1 H), 9.02 (d, 1 H).

Ligand Example 7

a) 7.2 g (0.12 mol) of 1,2-diaminoethane are added under nitrogen to36.6 g (0.10 mol) of 2,7-dibromo-9,10-phenanthrenedione in 1000 ml oftoluene. The red suspension is heated under reflux for one hour using awater separator. The resulting brownish suspension is diluted with 1000ml of toluene and treated with 25 g of manganese(IV)oxide at 84° C., andheating continued under reflux until no intermediate product is visibleanymore on the TLC (one hour reaction time). The hot black suspension isfiltered through silica gel (5 cm layer) using a preheated funnel, andthe silica gel layer rinsed with 500 ml of hot toluene. A solidimmediately precipitates out from the filtrate and is further washedwith a small amount of cold toluene, followed by drying in a vacuumoven, giving the title product as a white solid (yield: 30.9 g (80%)).¹H-NMR (400 MHz, CDCl₃): δ=7.91 (d, 2 H), 8.45 (d, 2 H), 8.96 (s, 2 H),9.39 (s, 2 H).

b) The title product is prepared according to the procedure of LigandExample 6, with 6, 11-dibromodibenzo[f,h]quinoxaline (product of LigandExample 7a), giving the title product as a white solid afterrecrystallization from ethanol.

Ligand Example 8

12.06 g (30.0 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]quinoxaline(product of Ligand Example 1b), and 6.65 g (90.0 mmol) of ethylboronicacid are suspended under argon in 200 ml of toluene. 0.27 (1.20 mmol) ofpalladium(II) acetate and 1.47 g (3.58 mmol) of2-dicyclohexyl-phosphino-2′,6′-dimethoxybiphenyl are added, followed bythe addition of 69 g (0.30 mol) of potassium phosphate hydrate. Thereaction mixture is degassed with argon and the light yellow suspensionheated under reflux for two hours. The hot grey suspension is filteredthrough silica gel (2 cm layer), and the silica gel layer rinsed withtoluene. The collected eluents are concentrated under vacuum and theresulting solid recrystallized three times from ethanol providing thetitle product as a light beige powder (yield: 4.98 g (55%)). Meltingpoint: 139-140° C. ¹H-NMR (400 MHz, CDCl₃): δ=1.44 (dt, 6 H), 2.85 (s, 3H), 2.96 (dq, 4 H), 7.57-7.63 (m, 2 H), 8.48 (d, 2 H), 8.75 (s, 1 H),9.51 (dd, 2 H).

Ligand Example 9

The title product is prepared according to the procedure of LigandExample 6, with 6, 11-dibromo-2-methyldibenzo[f,h]quinoxaline (productof Ligand Example 1b)), giving the title product as a white solid afterrecrystallization from ethanol.

Ligand Example 10

The title product is prepared according to the procedure of LigandExample 6, with 6, 11-dibromo-2-methyldibenzo[f,h]quinoxaline (productof Ligand Example 1b), giving the title product as a white solid afterrecrystallization from ethanol.

Ligand Example 11

4.02 g (10.0 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]quinoxaline(product of Ligand Example 1b), and 3.5 g (23.6 mmol) ofhexamethyldisilane are suspended under argon in 100 ml DMF and 0/2 g ofwater. 0.09 g (0.01 mmol) of tris(dibenzylideneacetone)dipalladium(0)and 0.06 g (0.18 mmol) of2-di-tert-butylphosphino-2′-(N,N-dimethylamino)biphenyl are added,followed by the addition of 3.3 g (50 mmol) of lithium acetate. Thereaction mixture is degassed with argon and the light yellow suspensionheated at 100° C. for 21 h. The hot grey suspension is treated with anadditional 3.5 g of hexamethyldisilane and heating continued at 109° C.for 4 h, followed by addition of the same amount of hexamethyldisilaneand heating at 109° C. for two hours. The grey suspension is filteredthrough silica gel (2 cm layer), and the silica gel layer rinsed with100 ml of DMF giving a clear yellow filtrate. The filtrate is treatedwith water until a beige suspension is obtained. The resulting solid isfiltered off and dissolved in 200 ml of a 1:1-mixture of hotethanol/isopropanol. The turbid mixure is filtered, cooled down to roomtemperature and treated with 5 ml of water providing a beige suspension.Filtration and drying in a vacuum oven gives the title product as alight beige solid. (yield: 1.9 g (49%)).

Ligand Example 12

8.53 g (22.0 mmol) of 6,11-dibromodibenzo[f, h]quinoxaline (product ofLigand Example 7a), and 4.90 g (66.3 mmol) of ethylboronic acid aresuspended under argon in 300 ml of toluene. 0.2 (0.89 mmol) ofpalladium(II) acetate and 1.08 g (2.63 mmol) of2-dicyclohexyl-phosphino-2′,6′-dimethoxybiphenyl are added, followed bythe addition of 50 g (0.22 mol) of potassium phosphate hydrate. Thereaction mixture is degassed with argon and the light yellow suspensionheated under reflux for two hours. The hot grey suspension is filteredthrough silica gel (2 cm layer), and the silica gel layer rinsed withtoluene. The collected eluents are concentrated under vacuum and theresulting solid recrystallized from ethanol providing the title productas a light beige powder (yield: 2.6 g (41%)).

Ligand Example 13

5.7 g (12.8 mmol) of the product of Ligand Example 5b), and 2.9 g (39.3mmol) of ethylboronic acid are suspended under argon in 200 ml oftoluene. 0.11 g (0.49 mmol) of palladium(II) acetate and 0.63 g (1.53mmol) of 2-dicyclohexyl-phosphino-2′,6′-dimethoxy-biphenyl are added,followed by the addition of 29.5 g (128.1 mmol) of potassium phosphatehydrate. The reaction mixture is degassed with argon and the lightyellow suspension heated under reflux for three hours. The hot greysuspension is filtered through silica gel (2 cm layer), and the silicagel layer rinsed with toluene. The collected eluents are concentratedunder vacuum and the resulting solid recrystallized from ethanol, givingthe title product as a white solid (yield: 3.3 g (73%)). Melting point:99-100° C. ¹H-NMR (400 MHz, CDCl₃): δ=1.09 (d, 6 H), 1.44 (dt, 6 H),2.34-2A7 (m, 1 H), 2.92-3.02 (m, 6 H), 7.61-7.67 (m, 2 H), 8.54 (d, 2H), 8.75 (s, 1 H), 9.02 (d, 1 H), 9.10 (d, 1 H).

Diiridium Complex Example 1

3.56 (10 mmol) of the product of Ligand Example 2 and 1.73 g (4.8 mmol)of indium(III)chloride hydrate (53.01% iridium-content) are suspended atroom temperature under nitrogen in 50 ml of 2-ethoxyethanol. The yellowsuspension is heated up to 116° C. and kept at this temperature for 17h. The red suspension is filtered, washed with ethanol first, followedby hexane, and further dried under vacuum, giving the title product asbright red powder (yield: 4.3 g (96%)).

Diiridium Complex Examples 2-7

The following diiridium complexes are prepared according to theprocedure reported for Diiridium Complex Example 1, giving the productsof Diiridium Complex Examples 2-6. The respective product structureshave been confirmed by HPLC-MS measurements.

Diiridium Complex Ligand Example Example Diiridium complex 1 2

2  1c)

3    4b)

4 6

5 8

6 13 

Complex Example 1

2.0 g (1.1 mmol) of the product of Diiridium Complex Example 1, and 1.1g (10 mmol) of sodium carbonate are suspended under nitrogen in 30 ml ofethoxyethanol. The red suspension is treated with 0.85 g (8.5 mmol) ofacetylacetone and stirred during one hour at 108° C. The resulting darkred suspension is filtered, rinsed with ethanol, and two times stirredin water. The remaining solid is further washed with ethanol and hexaneand then dried under vacuum at 50° C. The title product, compound A-31,is obtained as a bright red powder (yield: 1.74 g (76%)). The product isfurther purified by high vacuum sublimation. ¹H-NMR (300 MHz, CDCl₃):δ=−0.38 (d, 6 H), 0.03 (d, 6 H), 0.55-0.71 (m, 2 H), 1.03 (d, 12 H),1.35 (dd, 2 H), 1.64 (s, 6 H), 1.68 (dd, 2 H), 2.04-2.20 (m, 2 H), 2.80(d, 4 H), 2.88 (s, 6 H), 5.12 (s, 1 H), 7.01 (d, 2 H), 7.60 (dd, 2 H),8.00 (d, 2 H), 8.50 (s, 2 H), 8.51 (d, 2 H), 8.98 (d, 2 H).

Complex Examples 2-7

The iridium complexes A-2, A-88, A-37, A-17, A-73 and A-79 are preparedaccording to Complex Example 1, starting from the corresponding productsof Diiridium Complex Examples 2 to 6. The respective product structureshave been confirmed by HPLC-MS and NMR measurements.

¹H-NMR of A-2 (400 MHz, CDCl₃): δ=1.29 (s, 6 H), 1.72 (s, 6 H), 2.69 (s,6 H), 2.93 (s, 6 H), 5.23 (s, 1 H), 6.98 (d, 2 H), 7.64 (dd, 2 H), 7.95(d, 2 H), 8.49 (d, 2 H), 8.60 (s, 2 H), 9.04 (br. s, 2 H).

¹H-NMR of A-88 (300 MHz, CDCl₃): δ=−0.25 (d, 6 H), 0.07 (d, 6 H), 0.69(s, 18 H), 0.72-0.83 (m, 2 H), 1.03 (d, 12 H), 1.47 (dd, 2 H), 1.64 (dd,2 H), 2.05-2.20 (m, 2 H), 2.79 (d, 4 H), 2.84 (s, 6 H), 5.48 (s, 1 H),7.00 (d, 2 H), 7.61 (dd, 2 H), 7.99 (d, 2 H), 8.37 (s, 2 H), 8.52 (d, 2H), 8.96 (d, 2 H).

¹H-NMR of A-37 (400 MHz, CDCl₃): δ=−0.41 (d, 6 H), 0.06 (d, 6 H),0.59-0.72 (m, 2 H), 1.00-1.15 (m, 24 H), 1.42 (dd, 2 H), 1.63 (s, 6 H),1.75 (dd, 2 H), 2.09-2.20 (m, 2 H), 2.29-2.42 (m, 2 H), 2.76-2.88 (m, 4H), 2.91-3.05 (m, 4 H), 5.12 (s, 1 H), 7.04 (d, 2 H), 7.63 (dd, 2 H),8.03 (d, 2 H), 8.49 (s, 2 H), 8.53 (d, 2 H), 9.02 (d, 2 H).

¹H-NMR of A-17 (300 MHz, CDCl₃): δ=0.29 (t, 6 H), 1.45(t, 6 H),1.45-1.65 (m, 4 H), 1.67 (s, 6 H), 2.90 (s, 6 H), 2.98 (q, 4 H), 5.19(s, 1 H), 7.03 (d, 2 H), 7.66 (dd, 2 H), 8.01 (d, 2 H), 8.51 (d, 2 H),8.54 (s, 2 H), 9.05 (br. s, 2 H).

¹H-NMR of A-73 (400 MHz, CDCl₃): δ=0.38 (t, 6 H), 0.73 (s, 18 H), 1.48(t, 6 H), 1.61 (q, 4 H), 2.87 (s, 6 H), 3.00 (q, 4 H), 5.56 (s, 1 H),7.05 (d, 2 H), 7.69 (dd, 2 H), 8.03 (d, 2 H), 8.43 (s, 2 H), 8.55 (d, 2H), 9.06 (br. s, 2 H).

¹H-NMR of A-79 (300 MHz, CDCl₃): δ=0.27 (t, 6 H), 0.96-1.09 (m, 12 H),1.40-1.52 (m, 8 H), 1.63 (s, 6 H), 1.59-1.76 (m, 2 H), 2.26-2.42 (m, 2H), 2.86-3.06 (m, 8 H), 5.16 (s, 1 H), 7.04 (d, 2 H), 7.66 (dd, 2 H),8.01 (d, 2 H), 8.48 (s, 2 H), 8.52 (d, 2 H), 9.06 (br. s, 2 H).

The comparative complexes CC-1 to CC-7 are described in WO2009100991.

The photoluminescence (PL) spectra of the iridium complexes are measuredon thin polymer films doped with the respective iridium complexes. Thethin films are prepared by the following procedure: a 10%-w/w polymersolution is made by dissolving 1 g of the polymer “PMMA 6N” (Evonik) in9 g of dichloromethane, followed by stirring for one hour. 2 mg of therespective iridium complexes are added to 0.98 g of the PMMA solution,and stirring continued for one minute. The solutions are casted bydoctor-blading with a film applicator (Model 360 2082, Erichsen) with a60 μm gap onto quartz substrates providing thin doped polymer films(thickness ca. 6 pm). The PL spectra and quantum-yields (Q.Y.) of thesefilms are measured with the integrating-sphere method using the AbsolutePL Quantum Yield Measurement System (Hamamatsu, Model C9920-02)(excitation wavelength: 400 nm). The PL quantum efficiencies are givenrelative to Ir(MDQ)₂(acac) (CC-1), described in J.-P. Duan et al., Adv.Mat. 2003, 15, 224, with the PL Quantum Yield (Q.Y.) value ofIr(MDQ)₂(acac) given as 100%. The PL O.Y., λ_(max), CIE x, y and FWHM ofthe iridium complex doped PMMA films are shown in the table below:

Com- PL λ_(max) FWHM pound Structure of the Iridium complex Q.Y. (nm)CIE x, y (nm) CC-1

100% 615 0.62, 0.38 95 CC-2

101% 619 0.63, 0.37 94 CC-3

103% 612 0.62, 0.38 91 CC-4

100% 617 0.63, 0.37 98 CC-5

101% 621 0.65, 0.35 93 CC-6

100% 638 0.66, 0.34 94 CC-7

100% 628 0.67, 0.33 93 A-31

108% 618 0.64, 0.36 83 A-2

105% 618 0.64, 0.36 86 A-88

108% 621 0.65, 0.35 83 A-37

114% 612 0.63, 0.37 79 A-17

115% 619 0.64, 0.36 84 A-73

109% 623 0.65, 0.35 85 A-79

114% 613 0.63, 0.37 83

As evident from the above table, the iridium complexes of the presentinvention show deeper red color index coordinates (CIE x,y), narroweremission spectra with smaller full width of half maxima (FWHM) of theemission spectra, due to the fact that R³ and R⁸ represent alkyl groupsin comparison to iridium complexes described in WO2009100991, wherein R³and R⁸ represent H. Contrary to the teaching of EP1939208A1 said effectis achieved without introduction of an aryl group as R¹.

The photoluminescence (PL) spectra of the iridium complexes are measuredon thin α-NPD films doped with 4%-w/w of the respective iridiumcomplexes. The thin film samples are prepared by the followingprocedure: 1 mg of the the respective iridium complexes and 24 mg ofα-NPD are added to 2.5 mL of dichloromethane and the mixtures stirredfor 1-5 minutes. The resulting solutions are casted by doctor-bladingwith a film applicator (Model 360 2082, Erichsen) with a 30 μm gap ontoquartz substrates. The PL spectra aere measured as described for thePMMA films (excitation wavelength: 400 nm). The lifetime (w) of thephosphorescence of the iridium complexes in the prepared films aremeasured by the following procedure: For excitation of the emission asequence of short laser pulses (THG Nd-YAG, 355 nm, 1 nsec pulse length,1 kHz repetition rate) is used. The emissions are detected by thetime-resolved photon-counting technique in the multi-channel scalingmodus using a combination of photomultiplier, discriminator and amultiscaler card (FAST ComTec GmbH, Model P7888). The τ_(V), λ_(max),CIE x, y and FWHM of the iridium complex doped α-NPD films are shown inthe table below:

Cpd. λ_(max) (nm) CIE x, y FWHM (nm) τ_(v) (μs) CC-1 615 0.62, 0.38 901.83 CC-2 625 0.64, 0.36 99 1.64 CC-5 622 0.65, 0.35 92 3.15 A-31 6270.65, 0.35 86 1.44 A-88 630 0.66, 0.34 86 1.53 A-17 625 0.65, 0.35 781.37 A-37 615 0.64, 0.36 72 1.30 A-79 617 0.64, 0.36 73 1.34

As evident from the above table, the iridium complexes of the presentinvention show deeper red color index coordinates (CIE x,y), togetherwith narrower emission spectra with smaller full width of half maxima(FWHM) of the emission spectra, and a reduced triplet lifetime τ_(V) dueto the fact that R³ and R⁸ represent alkyl groups, in comparison toiridium complexes described in WO2009100991, wherein R³ and R⁸ representH.

The photoluminescence (PL) spectra of the iridium complexes are measuredin a concentration series on thin α-NPD films doped with either of2%-w/w, 5%-w/w, or 10%-w/w of the respective iridium complexes. Theα-NPD film samples of the concentration series are prepared by thefollowing procedure: 0.5 mg iridium complex and 24.5 mg α-NPD, 1.25 mgiridium complex and 23.75 mg α-NPD, 2.5 mg of iridium complex and 22.5mg α-NPD, are each added to 2.5 ml of dichloromethane. After stirringall mixtures for 1-5 min the solutions casted by doctor-blading with afilm applicator (Model 360 2082, Erichsen) with a 30 μm gap onto quartzsubstrates. The PL spectra are measured as described above (excitationwavelength: 400 nm). The λ_(max), CIE x, y and FWHM of the iridiumcomplex doped α-NPD films are shown in the table below:

2% in α-NPD 5% in α-NPD 10% in α-NPD λ_(max) CIE FWHM λ_(max) CIE FWHMλ_(max) CIE FWHM (nm) x, y (nm) (nm) x, y (nm) (nm) x, y (nm) CC-1 6150.62 86 616 0.63 90 627 0.64 94 0.38 0.37 0.36 A-37 615 0.64 70 620 0.6577 622 0.65 79 0.36 0.35 0.35 A-17 619 0.64 77 623 0.65 78 626 0.65 780.36 0.35 0.35 A-31 620 0.64 76 623 0.65 83 628 0.66 87 0.36 0.35 0.34A-88 625 0.65 80 629 0.66 83 628 0.66 84 0.35 0.34 0.34

As evident from the above table, the iridium complexes of the presentinvention show deeper red color index coordinates (CIE x,y), togetherwith narrower emission spectra with smaller full width of half maxima(FWHM) of the emission spectra over a broad range of concentrationswhich are relevant for application of the claimed complexes. The colorindex coordinates (CIE x,y) can be also less dependent from the amountof emitter used in the matrix material as in the case of the iridiumcomplexes described in WO2009100991.

Comparative Application Example 1

The ITO substrate used as the anode is first cleaned with anacetone/isopropanol mixture in an ultrasound bath. To eliminate anypossible organic residues, the substrate is exposed to a continuousozone flow in an ozone oven for further 25 minutes. This treatment alsoimproves the hole injection properties of the ITO. Then Plexcore® OCAJ20-1000 (commercially available from Plextronics Inc.) is spin-coatedand dried to form a hole injection layer (˜40 nm).

Thereafter, the organic materials specified below are applied by vapordeposition to the clean substrate at a rate of approx. 0.5-5 nm/min atabout 10⁻⁷-10⁻⁹ mbar. As a hole transport and exciton blocker,

for preparation, see iridium complex (7) in patent applicationWO2005/019373), is applied to the substrate with a thickness of 20 nm,wherein the first 10 nm are doped with MoO_(x) (˜10%) to improve theconductivity.

Subsequently, a mixture of 10% by weight of emitter compound

and 90% by weight of compound

is applied by vapor deposition in a thickness of 20 nm.

Subsequently, BAlq

is applied by vapour deposition with a thickness of 10 nm as blocker. Anadditional layer of BCP

doped with Cs₂CO₃ is applied as electron transport layer by vapordeposition in a thickness of 50 nm and finally a 100 nm-thick Alelectrode completes the device.

All fabricated parts are sealed with a glass lid and a getter in aninert nitrogen atmosphere.

To characterize the OLED, electroluminescence spectra are recorded atvarious currents and voltages. In addition, the current-voltagecharacteristic is measured in combination with the light output emitted.The light output can be converted to photometric parameters bycalibration with a photometer. To determine the lifetime, the OLED isoperated at a constant current density and the decrease in the lightoutput is recorded. The lifetime is defined as that time which lapsesuntil the luminance decreases to half of the initial luminance.

Comparative Application Example 2

The device of Comparative Application Example 2 is prepared as thedevice of Comparative Application Example 1, except that compound CC-3is used instead of compound CC-1

Application Examples 1 and 2

The device of Application Examples 1 and 2 is prepared as the device ofComparative Application Example 1, except that compound A-79 and (A-17),respectively are used instead of compound CC-1.

λ_(max) CIEx CIEy FWHM U[V] cd/A Im/W EQE Comp. 615 0.63 0.37 88 3.0418.7 19.4 12.6 Appl. Ex. 1 (CC-1) Comp. 608 0.62 0.38 84 3.06 28 28.816.1 Appl. Ex. 2 (CC-3) Appl. Ex. 1 614 0.64 0.36 71 3.35 25 23.5 16.2(A-79) Appl. Ex. 2 619 0.65 0.35 76 3.38 22.4 20.9 16.7 (A-17)

As evident from the above table, the iridium complexes of the presentinvention show deeper red color index coordinates (CIE x,y), togetherwith narrower emission spectra with smaller full width of half maxima(FWHM) of the emission spectra, at high EQE, due to the fact that R³ andR⁸ represent alkyl groups in comparison to iridium complexes describedin WO2009100991, wherein R³ and R⁸ represent H. Reference is made toFIG. 1, which provides a plot of the EL intensity of compounds CC-1 andA-17 as a function of wavelength, and FIG. 2, which provides a plot ofthe EL intensity of compounds CC-3 and A-79 as a function of wavelength.

Comparative Complex Example 1 (complex CC-8=complex A-156 described inWO2009/100991)

a) 10.0 g (24.9 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]quinoxaline(product of Ligand Example 1b), and 9.1 g (74.6 mmol) of phenylboronicacid are suspended under argon in 250 ml of toluene. 0.22 g (1.0 mmol)of palladium(II) acetate and 1.23 g (3.0 mmol) of2-dicyclohexyl-phosphino-2′,6′-dimethoxybiphenyl are added, followed bythe addition of 57.3 g (0.25 mol) of potassium phosphate hydrate. Thereaction mixture is degassed with argon and the light yellow suspensionheated under reflux for two hours. The hot grey suspension is filteredthrough Celite, and the Celite layer several times extracted with 200 mlof hot toluene. The collected eluents are concentrated under vacuum andthe resulting solid recrystallized from ethanol, giving the titleproduct as a white solid (yield: 5.1 g (52%)). Melting point: 288-290°C. ¹H-NMR (400 MHz, CDCl₃): δ=2.80 (s, 3 H), 7.32-7.40 (m, 2 H),7.43-7.52 (m, 4 H), 7.81 (d, 4 H), 7.94-8.01 (m, 2 H), 8.63 (d, 2 H),8.74 (s, 1 H), 9.39 (d, 1 H), 9.45 (d, 1 H).

b) The diiridium complex intermediate is prepared first according to theprocedure reported for Diiridium Complex Example 1, with 1.11 g (2.8mmol) of the product of Comparative Complex Example 2a), 0.48 g (1.3mmol) of iridium(III)chloride hydrate and 30 ml of 2-ethoxyethanol,giving the diiridium complex intermediate as an orange powder (1.24 g,92%). In a next step, the comparative complex CC-8 is prepared accordingto Complex Example 1, with 1.19 g (0.58 mmol) of diiridium complexintermediate isolated before, 0.62 g (5.8 mmol) of sodium carbonate,0.47 g (4.7 mmol) of acetylacetone and 20 ml of 2-ethoxyethanol, givingthe comparative complex CC-8 as an orange powder after extensivepurification (1.08 g, 85%), with a HPLC-purity of >99% at 250 nmUV-detection. APCI-LC-MS (negative, m/z): exact mass=1082.32 g/mol;found 1082.1 [M]⁺. APCI-LC-MS t(posiive, m/z): exact mass=1082.32 g/mol;found 1083.2 [M+1]⁺.

Comparative Complex Example 2 (complex CC-9 =complex A-18 described inWO2009/100991)

a) 8.0 g (19.9 mmol) of 6,11-dibromo-2-methyldibenzo[f,h]quinoxaline(product of Ligand Example 1b), and 9.91 g (59.7 mmol) of4-ethoxyphenylboronic acid are suspended under argon in 250 ml oftoluene. 0.18 g (0.8 mmol) of palladium(II) acetate and 0.98 g (2.4mmol) of 2-dicyclohexyl-phosphino-2′,6′-dinnethoxybiphenyl are added,followed by the addition of 45.8 g (0.20 mol) of potassium phosphatehydrate. The reaction mixture is degassed with argon and the greysuspension heated under reflux for 21 hours. The hot grey suspension isfiltered through Celite, and the Celite layer several times extractedwith 200 ml of hot toluene. The collected eluents are concentrated undervacuum giving the title product as a light yellow solid (yield: 4.0 g(41%)). Melting point: 310-312° C. ¹H-NMR (300 MHz, CDCl₃): δ=1.45-1.56(m, 6 H), 2.90 (s, 3 H), 4.11-4.20 (m, 4 H), 7.04-7.13 (m, 4 H), 7.84(d, 4 H), 7.98-8.07 (m, 2 H), 8.68 (d, 2 H), 8.83 (s, 1 H), 9.43 (d, 1H), 9.49 (d, 1 H).

b) The diiridium complex intermediate is prepared first according to theprocedure reported for Diiridium Complex Example 1, with 1.3 g (2.7mmol) of the product of Comparative Complex Example 2a), 0.46 g (1.3mmol) of iridium(III)chloride hydrate and 50 ml of 2-ethoxyethanol,giving the diiridium complex intermediate as a red powder (1.50 g, 99%).In a next step, the comparative complex CC-9 is prepared according toComplex Example 1, with 1.5 g (0.63 mmol) of diiridium complexintermediate isolated before, 0.67 g (6.3 mmol) of sodium carbonate, 0.5g (5.0 mmol) of acetylacetone and 20 ml of 2-ethoxyethanol, giving thetitle complex as a red powder after extensive purification (1.49 g,94%).

Photoluminescence spectra of complexes CC-1, CC-8, A-37 and A-17 havebeen measured in PMMA films as described above and are shown in thetable below.

PL λ_(max) Compound Structure of the Iridium complex Q.Y. (nm) CIE x, yCC-1

100% 615 0.62, 0.38 CC-8

111% 587 0.57, 0.43 A-37

114% 612 0.63, 0.37 A-17

115% 619 0.64, 0.36

As is evident from the above table, the comparative complex CC-8 doesnot lead to a deeper red color point compared to the complexes of thepresent invention. CC-8 shows a large green-shift of the emissionspectra with CIE x,y of (0.57, 0.43) due to the extended conjugation byphenyl groups attached to the R³ and R⁸ positions. Complex CC-8 does notsublime at pressures down to 10⁻⁶ to 10⁻i mbar and is not suitable for avacuum deposition process, but leads to degradation with increase oftemperature. Thermal gravimetric analysis (TGA) of complex CC-8 shows aweight loss with an onset temperature of 240-250° C. By contrast,complexes of the present invention show high sublimation yieldsof >70-80% based on much higher thermal stability and volatility, withonset temperatures in TGA of above 330° C.

Complex CC-9 is not soluble and does not sublime at pressures down to10⁻⁶ to 10⁻⁷ mbar and is not suitable for a vacuum deposition process,but leads to degradation with increase of temperature. Thermalgravimetric analysis (TGA) of complex CC-9 shows a weight loss with anonset temperature of 200-210° C. Complexes of the present invention showhigh sublimation yields of >70-80% based on much higher thermalstability and volatility, with onset temperatures in TGA of above 330°C.

1.-14. (canceled)
 15. A compound of formula

wherein X is H, methyl, or ethyl, L^(a) is

wherein R¹ ^(H, C) ₃-C₈cycloalkyl, which is optionally substituted byC₁-C₈alkyl, or C₁-C₈perfluoroalkyl, or C₁-C₈alkyl, and R² is H, orC₁-C₈alkyl, or R¹ is a group of formula

and R² is H; R⁴ is C₁-C₈alkyl, CF₃, or NR⁷R⁹, R^(4′) is H, CF₃ orC₁-C₈alkyl R^(4″) is C₁-C₈alkyl, or CF₃, R⁷ and R⁹ are independently ofeach other

or R⁷ and R⁹ together with the nitrogen atom to which they are bondedform a group of formula

R¹⁰ is H, or C₁-C₈alkyl, or R¹ and R² together form a ring —(CH₂)₃—, or—(CH₂)₄—, which are optionally substituted by one or two C₁-C₈alkyland/or by one or two C₁-C₈perfluoroalkyl, and R³ and R⁸ areindependently of each other C₁-C₈alkyl, —Si(C₁-C₈alkyl)₃, orC₃-C₈cycloalkyl.
 16. The compound according to claim 15, wherein R¹ andR² together form a ring —(CH₂)₃—, or —(CH₂)₄—, which are optionallysubstituted by one, or two C₁-C₈alkyl and/or by one, or twoC₁-C₈perfluoroalkyl.
 17. The compound according to claim 15, wherein R¹is a group of formula

R⁴ is C₁-C₈alkyl, CF₃, or NR⁷R⁹, R^(4″) is C₁-C₈alkyl, or CF₃, R⁷ and R⁹are independently of each other

R⁷ and R⁹ together with the nitrogen atom to which they are bonded forma group of formula

R¹⁰ is H, or C₁-C₈alkyl, and R²is H.
 18. The compound according to claim15, wherein R³ and R⁸ are independently of each other C₁-C₈alkyl,—Si(C₁-C₄alkyl)₃, or C₃-C₆cycloalkyl.
 19. The compound according toclaim 15, wherein R² is H.
 20. The compound according to claim 15,wherein R¹ is C₁-C₈alkyl.
 21. The compound according to claim 15,wherein R³ and R⁸ are each C₁-C₈alkyl.
 22. An organic electronic device,comprising the compound according to claim
 15. 23. An emitting layercomprising the compound according to claim
 15. 24. The emitting layeraccording to claim 23, comprising the compound in combination with ahost material.
 25. An apparatus selected from the group consisting of astationary visual display unit; an illumination unit; a keyboard; anitem of clothing; an item of furniture; and wallpaper, comprising theorganic electronic device according to claim
 22. 26. Anelectrophotographic photoreceptor, photoelectric converter, organicsolar cell, switching element, organic light emitting field effecttransistor, image sensor, dye laser or electroluminescent devicecomprising the compound according to claim 15.